Full opinion text
MEMORANDUM OPINION AND ORDER ASPEN, District Judge: Today we resolve the following challenges to the constitutionality of the Illinois death penalty scheme, Ill.Rev.Stat. ch. 38, 119-1: (1) that the statute and jury instructions impose a presumption in favor of death in violation of the Eighth and Fourteenth Amendments of the United States Constitution (Ground 5) ; (2) that the act is unconstitutionally vague and fails to narrowly channel and guide the sentencing authority’s discretion, thereby creating the impermissible risk that the death sentence will be imposed arbitrarily and capriciously (Ground 10); and (3) that the failure of the Illinois sentencing scheme to assign a specific standard of proof as to the ultimate issue renders the scheme unconstitutional (Ground 14). As noted in our order dated November 5, 1991, see United States ex rel. Free v. Peters (“Free IV”), 778 F.Supp. 431, 434 (N.D.Ill.1991), each of the above contentions has been rejected either by the Seventh Circuit in Silagy v. Peters, 905 F.2d 986 (7th Cir.1990), cert. denied, — U.S. —, 111 S.Ct. 1024, 112 L.Ed.2d 1106 (1991), or by this court in Williams v. Chrans, 742 F.Supp. 472 (N.D.Ill.1990), aff'd, 945 F.2d 926 (7th Cir.1991), cert. denied, — U.S. —, 112 S.Ct. 3002, 120 L.Ed.2d 877 (1992). Nevertheless, we concluded that Free’s proffer of a jury survey conducted in April of 1990 by Professor Hans Zeisel, along with an affidavit by Professor Zeisel interpreting the results of that survey, “call[s] into question the empirical assumptions as to juror comprehension which served as the predicate to the rulings in both [Silagy and Williams ].” Free IV, 778 F.Supp. at 434-35. Consequently, we referred the matter to Magistrate Judge Bernard Weisberg to assess (1) the validity of the Zeisel study, and (2) its impact on each of the grounds (5, 10 & 14) for which it is offered as support. Id. at 436. Magistrate Judge Weisberg conducted an evidentiary hearing on January 13, 14 and 15, and February 4, 5 and 7,1992, at which various expert witnesses testified regarding empirical jury studies, statistics, survey methodology and linguistics. Much of the January testimony focused on the similarity between the 1987 Illinois Pattern Instructions (“IPI”), utilized in the April 1990 study, and the actual jury instructions provided at the Free sentencing. In order to preempt the issue, during the January recess, Dr. Zeisel conducted a second survey identical in all respects to the previous study, but substituting the Free instructions in the place of the 1987 IPI instructions. Both surveys were designed to test juror comprehension of the following five issues: (1) whether a jury must unanimously agree on the existence of a mitigating factor before that factor can be considered by an individual juror (questions 4 and 5); (2) whether the jury may properly consider mitigating factors not enumerated in the jury instructions (questions 1, 2, 6, 7-, 8, 9, 10, and 11); (3) whether the existence of a mitigating factor bars a sentence of death (question 3); (4) which side shoulders the burden of proof on the appropriate sentence (questions 12, 13, 14 and 15); and (5) whether a jury which is divided on the penalty issue should return a verdict or tell the judge they cannot reach a unanimous verdict (question ■ 16). On July 7, 1992, Magistrate Judge Weis-berg filed and served upon the parties his Report and Recommendation, fifty-two pages in length. After careful and thoughtful consideration, Magistrate Judge Weisberg found “that the Zeisel surveys are valid, meaning that within standard margins of error the survey results are true, that is, they fairly represent the levels of comprehension of the survey respondents regarding the capital sentencing instructions used in those surveys.” Report and Recommendation at 20. Considering the impact of the studies on Free’s case, Magistrate Judge Weisberg determined that “there is a reasonable likelihood that a substantial number of jurors who received the IPI instructions and [a substantial number] of Free’s jurors believed that only the statutory mitigating factors, or factors comparable to them, could preclude the imposition of the death penalty.” Id. at 36. Further, the Magistrate Judge concluded that “the Free jury, like juries receiving the IPI instructions, was probably confused about which side, if any, had a burden of persuasion and what the nature of that burden was.” Id. at 46. Accordingly, Magistrate Judge Weisberg recommended that Free’s petition for habeas relief be granted with respect to Grounds 5, 10 and 14. Both Free and respondents have filed timely objections to the Magistrate Judge’s Report and Recommendation. In Section I of this opinion, we will address respondents’ procedural challenges to the propriety of the hearing before Magistrate Judge Weisberg, including questions respecting the burden of proof, procedural default, failure to factually develop legal claims and standing to challenge the IPI instructions. Section II will consider respondents’ objections to Magistrate Judge Weisberg’s determination that the Zeisel studies are statistically reliable and valid. Finally, Section III will resolve the parties’ exceptions to the Magistrate Judge’s assessment of the impact of the empirical evidence on Free’s remaining claims (Grounds 5, 10 & 14). ' I. Challenges to the Propriety of the Proceedings Before the Magistrate Judge A. Burden of Proof Respondents begin their attack on the Report and Recommendation by arguing that the Magistrate Judge improperly shifted the burden of proof to the respondents to produce evidence that the studies are invalid. Respondents are mistaken. To be sure, the burden of proving that “there is a reasonable likelihood that the jury has applied the challenged instruction^] in [a manner inconsistent with the dictates of the United States Constitution]” rests upon Free during the entirety of these proceedings. See Boyde v. California, 494 U.S. 370, 380, 110 S.Ct. 1190, 1198, 108 L.Ed.2d 316 (1990); Williams v. Chrans, 945 F.2d 926, 938 (7th Cir.1991), cert. denied, — U.S. —, 112 S.Ct. 3002, 120 L.Ed.2d 877 (1992). As distinguished from the burden of proof, the duty of going forward with evidence necessarily shifts from side to side as the proceedings progress, according to the nature and strength of the evidence offered in support or denial of the proposition to be established. 9 John Henry Wigmore, Evidence § 2487, at 292-97 (Chadbourn rev. 1981). Bearing the burden of proof, Free also shoulders the initial duty of producing evidence (i.e., establishing a prima facie case that it is reasonably likely that his jurors applied the jury instructions impermissibly). Id. at 293. Once Free has satisfied this duty, a presumption in his favor arises requiring respondents to produce evidence in rebuttal. Id. at 294-95. In order to meet his initial burden of production, Free presented the testimony of several notable experts on jury decision-making, juror comprehension and jury research methodology. Professor Hans Zeisel, “a scholar of unquestionable objectivity,” Report and Recommendation at 28, testified to the design and administration of the surveys, as well as the reliability and significance of the results. Likewise, Professors Shari Diamond, Valerie Hans and Peter Rossi, experts in statistics, jury deci-sionmaking and jury research methodology, testified to the reliability of, and implications flowing from, the survey data. Further, Free presented the testimony of Professor Judith Levi, a respected scholar in the field of linguistics, which addressed the similarity of the IPI and Free instructions and the sources of miscomprehension likely to arise from those sets of jury instructions. Faced with this substantial and credible evidence, Magistrate Judge Weis-berg properly concluded that Free’s proffer had established a prima facie case. Consequently, the burden of production shifted to respondents to present evidence in rebuttal. Respondents relied exclusively on the testimony of Dr. Paul J. Lavrakas, a professor of journalism and expert in research methodology. As discussed infra Section II, Magistrate Judge Weisberg considered Lavrakas’ criticisms of the Zeisel surveys in great detail, rejecting his appraisal and concluding that the studies are reliable and valid. Report and Recommendation at 15-24. In reaching his conclusion, Magistrate Judge Weisberg necessarily had to weigh competing testimony and make certain credibility decisions. This, process, however, does not evince an impermissible shifting of either the burden of proof or production. Other than disagreeing with the substance of the Magistrate Judge’s conclusion, respondents imply that, in order to meet his burden via statistical evidence, Free must eliminate all alternative hypotheses. This, however, is a misstatement of Free’s burden. See Allen v. Seidman, 881 F.2d 375, 380 (7th Cir.1989) (“The Corporation’s attack on the plaintiffs’ statistical case amounts to a contention that unless a plaintiff eliminates all alternative hypotheses he must lose. That would raise the threshold of proof too high.”). We cannot conclude that Magistrate Judge Weisberg impermissibly shifted the burden of proof to respondents merely because he declined to accept the unsupported speculation of their expert witness. B. Procedural Default In a post-hoc attempt to nullify portions of the proceedings before Magistrate Judge Weisberg in their entirety, respondents assert that each of Free’s current claims are procedurally defaulted, with the exception of (1) the portion of Ground 10 alleging that the jury instructions given at his sentencing hearing did not provide the jury with sufficient guidance on whether non-statutory mitigating factors may be considered, and (2) the allegation in Ground 5 that the death penalty statute and jury instructions created an unconstitutional presumption in favor, of death. However, as poignantly noted by Free, respondents’ contention is not an objection to the Magistrate Judge’s Report and Recommendation, but rather a request for reconsideration of our previous ruling. On November 5,1991, this court unequivocally held that the constitutional bases of Grounds 10 and 14 were “fairly presented” to the Illinois Supreme Court on direct appeal. Free IV, 778 F.Supp. at 435-36 n. 3. Respondents’ argument is not only improperly before the court at this time, but devoid of any showing of a manifest error of law or fact. Consequently, respondents’ “objection” to the propriety of the proceedings via the procedural default doctrine is overruled. C. Failure to Factually Develop Legal Claims In light of the recent Supreme Court decision in Keeney v. Tamayo-Reyes, — U.S. —, 112 S.Ct. 1715, 118 L.Ed.2d 318 (1992), respondents argue that Free’s failure to develop the factual predicate for Grounds 5, 10 and 14 in state court precludes a federal hearing on the matter. We disagree. In Tamayo-Reyes, petitioner, a Cuban immigrant with minimal education and almost no knowledge of the English language, plead nolo contendere to first-degree manslaughter. Id. — U.S. at —, 112 S.Ct. at 1716. In a state collateral attack on the plea, Tamayo-Reyes maintained that his plea had not been knowing and intelligent because his translator had not explained the nature of the plea agreement or the mens rea element of manslaughter. Id. Following a hearing, the state court dismissed Tamayo-Reyes’s petition, finding that the interpreter fully and accurately translated the colloquy during the plea hearing. Id. — U.S. at —, 112 S.Ct. at 1716-17. Tamayo-Reyes brought a petition for habeas relief in federal district court, arguing that the material facts concerning the translation were not sufficiently developed during the state-court hearing. Id. — U.S. at —, 112 S.Ct. at 1717. Reversing the Ninth Circuit and overruling Townsend v. Sain, 372 U.S. 293, 83 S.Ct. 745, 9 L.Ed.2d 770 (1963), the Supreme Court held that, to be entitled to an evidentiary hearing in federal coúrt, a ha-beas petitioner must show cause for and demonstrate actual prejudice from his failure to adequately develop the evidentiary basis of his claims in state-court proceedings. Tamayo-Reyes, — U.S. at —, 112 S.Ct. at 1721. In the instant case, although Free fairly presented his present claims on direct appeal, it is undisputed that the evidentiary basis for those claims — i.e., the Zeisel studies — was never presented to the Illinois courts, either on direct appeal or in a petition for post-conviction relief. Nonetheless, assuming that Tamayo-Reyes applies retroactively and, as such, that Free must show cause for and prejudice from his failure to present the Zeisel surveys to the state courts prior to seeking federal habeas relief, the instant case presents the rare circumstance wherein this heightened level of scrutiny is met. Establishing “cause” ordinarily requires a showing of some external impediment preventing counsel from constructing or raising the evidence. Tamayo-Reyes, — U.S. at — - — n. 5, 112 S.Ct. at 1720-21 n. 5 (citing Murray v. Carrier, 477 U.S. 478, 492, 106 S.Ct. 2639, 2648, 91 L.Ed.2d 397 (1986)). The evidence adduced at the hearing before Magistrate Judge Weisberg clearly supports the proposition that empirical data such as the results of the Zeisel studies “was unavailable to Free at the time of his prior state court petitions.” Free IV, 778 F.Supp. at 436 n. 3. The relevant question for purposes of the present inquiry is whether Free and his attorneys could have carried out a study similar to those conducted by Zeisel, and not whether Zeisel himself could have performed the survey at an earlier date. Magistrate Judge Weisberg found, and we agree, that the initial Zeisel study conducted in April of 1990, represented an effort entirely independent from Free and his attorneys. Report and Recommendation at 27. Indeed, the survey was commissioned by David Bradford, a lawyer working for the Mac Arthur Justice Center. Transcript at 18-19, 60-61 (testimony of Prof. Zeisel). The only involvement by Free and his attorneys in the creation or conduct of the 1990 Zeisel study was the grant of permission to use the facts of the Free case. Transcript at 4, lines 10-14 (statement of Kimball Anderson). Having established the independence of the study, it follows that Free could not have reasonably produced such empirical evidence on his own initiative pri- or to April of 1990 (i.e., Free could only wait for the existence of the Zeisel survey data). In an effort to rebut this conclusion, respondents could have, proffered evidence indicating a reasonable probability that Free could have obtained (1) another academic expert in jury research willing to conduct such a survey at Free’s request, and (2) access to either the Cook County or DuPage County Circuit Court jury panels. Respondents, however, did not. Report and Recommendation at 27. Clearly, Free received a windfall in that the principles Zeisel and Bradford sought to establish necessarily must arise in the context of a specific case and, of all the appeals involving Illinois capital defendants, they chose Free. Transcript at 86, lines 8-15 (testimony of Prof. Zeisel). Nonetheless, that fortune does not negate the fact that until the Zeisel survey was conducted in April of 1990, such empirical data was not reasonably available to Free at the time of his prior state-court proceedings. Finding sufficient Free’s showing of cause for his failure to develop the factual foundation of his legal claims, we are left with the question of whether Free has established “actual prejudice” for the default. As noted by Magistrate Judge Weisberg, this issue hinges on the applicability of the Zeisel survey results to the Free jury itself. Report and Recommendation at 26 n. 8. Based on the conclusions drawn infra Section III, we hold that Free’s failure to produce similar empirical evidence during his prior state-court proceedings does not bar this court from considering the Zeisel studies in support of Grounds 5, 10 and 14. D. Standing to Challenge the IPI Instructions The gravamen of respondents’ standing argument is that the Free jury did not receive the IPI instructions used in the 1990 Zeisel survey and, as such, Free was not “entitled to have the court decide the merits of any claims challenging the use of those instructions.” Respondent’s Objections to Report and Recommendation at 23-24. This contention, however, misses the mark. Indeed, Free does not claim that his death sentence must be vacated because the IPI instructipns do not pass constitutional muster. Rather, the basis of Free’s current petition is that the specific instructions given to his jury at sentencing did not provide them with constitutionally sufficient guidance. The relevance of the IPI instructions, and thus the relevance of the 1990 Zeisel survey testing juror comprehension on the basis of those instructions, comes with their similarity to the actual Free instructions. Assuming the IPI instructions are substantially similar to those used in Free, that the IPI instructions utilized in the 1990 Zeisel study did not provide jurors with constitutionally adequate guidance is a reasonable indication that neither did the Free instructions. Consequently, we turn to consider the similarity of the two sets of instructions. ■ To establish the substantial similarity between the IPI and Free jury instructions, both of which meticulously track the language of the Illinois death penalty statute, Free presented the expert testimony of Professor Judith Levi, a linguistics scholar specializing in the interaction between language and the law. Professor Levi prepared and presented detailed exhibits comparing the IPI instructions to those used in Free, concluding that the two sets of jury instructions are substantially similar in all material respects. Indeed, to the extent that minor language variations appear between the IPI and Free instructions, Professor Levi concluded that in the vast majority of those cases the Free instructions provided less guidance than the IPI instructions used in the 1990 Zeisel study. Transcript at 548-61. For example, with respect to the whether the jury may properly consider non-statutory mitigating factors, the IPI instructions state in relevant part: Mitigating factors include: That the murder was committed while the defendant was under the influence of an extreme mental or emotional disturbance, although not such as to constitute a defense to the prosecution. The defendant has no significant history of prior criminal activity. The murdered person was a participant in the defendant’s homicidal conduct or consented to the homicidal act. The defendant acted under the compulsion of threat or menace of the imminent infliction of death or great bodily harm. The defendant was not personally present during the commission of the act or acts causing death. The defendant may be rehabilitated or restored to useful citizenship. Any other reason supported by the evidence why the defendant should not be sentenced to death. The Free instructions, on the other hand, provide: Mitigating factors include but are not limited to the following circumstances. One, the Defendant has no significant history of prior criminal activity. Two, the murder was committed while the Defendant was under the influence of extreme mental or emotional disturbance, although not such as to constitute a defense to prosecution. If, from your consideration of the evidence, you find that any of the above mitigating factors are present in this case, or that any other mitigating factors are present in this case then you should consider such factors in light of any existing aggravating factors in determining whether the death sentence shall be imposed. Professor Levi explained that for two distinct reasons the Free instructions provide less guidance than the IPI jury instructions on the issue of non-statutory mitigating factors. First, as a matter of syntax, the IPI instructions present a list of mitigating factors as examples and include as a separate item in that list “[a]ny other reason supported by the evidence why the defendant should not be sentenced to death.” On the other hand, the idea that jurors may properly consider mitigating factors not explicitly listed in the instructions is expressed in the Free instructions in a subordinate clause “imbedded inside of a complex instruction.” This difference in syntax renders the Free instructions inferior to the IPI jury instructions. Transcript at 488-89, 542. Second, the IPI instructions include as an example “[t]he defendant may be rehabilitated or restored to useful citizenship.” According to Professor Levi, this example is qualitatively different than any of the others in that it focuses on the future, as opposed to the crime itself or the past in general. Transcript at 543, lines 1-15. Because such an example is not given in the Free instructions, those instructions “give a much more limited impression to the jurors of what they can count as mitigating factors.” Transcript at 543, lines 17-19. Respondents’ attempt to rebut this credible and substantial evidence comes in the form of a statement made by Professor Zeisel that “there may be points where the difference [between the two sets of instructions] is considered great enough so that my survey does not apply.” Transcript at 41, lines 23-25. When placed in context, however, respondents’ use of Zeisel’s statement is nothing more than disingenuous. Immediately following his speculation, Professor Zeisel stated “the point I want to make is that I would not like to get into this discussion_ It is not my expertise.” Transcript at 42, lines 1-3. Indeed, as respondents’ counsel pressed Zeisel on cross-examination to compare the two sets of instructions, he emphatically stated: Mr. Schwind, I think you might have heard me on direct examination, that I beg of you not to go with me into the distinctions between the Free instructions and the instructions I used.... Because I haven’t studied it. Besides it’s not my competence as a researcher to make this judgments [sic], and as I suggested, the Court might have to do it, and I asked specifically at that time’ that you on cross should not go into this matter with me. Transcript at 64, lines 16-25. In the absence of any evidence rebutting the Magistrate’s well-founded conclusion that the two sets of instructions are substantially similar, we reject respondents’ standing argument and find that the 1990 Zeisel survey is relevant in the determination of whether Free’s jury received constitutionally adequate guidance. II. Statistical Reliability and Validity of the Zeisel Surveys A. Documentation Respecting the Population Surveyed Professor Lavrakas testified that in his opinion “there was insufficient documentation for understanding what the population or the universe was.” Transcript at 900, lines 12-14. Based on this opinion, respondents maintain that the Zeisel studies lack “construct validity,” i.e., whether a research instrument measures what it is claimed to measure. Professor Zeisel, however, testified in great detail as to the creation, methodology and administration of the survey, and set forth the precise population from which he drew his sample. Professor Lavrakas’ confusion over this point likely stems from the fact that he was not present for the majority of Zeisel’s testimony. See Transcript at 918, lines 18-19 (statement of Prof. Lavrakas). To be sure, Professor Zeisel defines the universe for his surveys as potential jurors from Cook County who are eligible to sit on a capital case. Transcript at 49, lines 12-25. In light of the extensive testimony on the matter, we find respondents’ objection to the lack of documentation frivolous. B. Relevance of “Statistically Significant” Evidence Respondents concede that Free has in fact established that “Zeisel’s survey data reveal a pattern of incorrect answers on the part of the participants that is significant at both the .05 and .01 levels.” Respondents’ Objections to Report and Recommendation at 4. Nonetheless, respondents contend that the evidence does not support the proposition that this pattern of incorrect responses indicates miscompre-hension on the part of the potential jurors surveyed. In other words, statistical significance in itself does not show that there is a substantial causal relationship between the incorrect answers and juror miscompre-hension. Indeed, “[a]n explanatory theory and consideration of the surrounding facts is necessary to determine if there is a causal relationship.” Dixon v. Margolis, 765 F.Supp. 454, 459 n. 8 (N.D.Ill.1991) (citing Tagatz v. Marquette University, 861 F.2d 1040, 1045 (7th Cir.1988)). Magistrate Judge Weisberg found that “[t]he Zeisel surveys on their face appear to be designed to measure jury comprehension of capital sentencing instructions,” Report and Recommendation at 16, and the weight of the evidence adduced at the hearing supports this assertion. See Transcript at 45, lines 22-25 (The purpose of the surveys was “to test whether the — these instructions had created thoughts in the minds of the jurors who listened to them which led to potentially to unconstitutional decisions.”) (statement of Prof. Zeisel); Transcript at 22-23 (As described by Prof. Zeisel, each question gives an example of some judgments jurors made in the hypothetical case and then asks whether the jurors followed the instructions, not whether they got the right or wrong result.); Transcript at 129, lines 10-17 (“[I]n terms of research design, and the study design, the purpose of the study, as I understood it, was to examine juror comprehension of the instructions, the judicial instructions. And that method that was adopted by Hans Zeisel is one that is commonly used, and the research field generally accepted as an appropriate scientific method for examining juror comprehension.”) (statement of Prof. Hans); Transcript at 408, lines 4-6 (The Zeisel study “was specifically designed to test the jurors comprehension of the Illinois death penalty instructions.”) (statement of Prof. Diamond); Transcript at 609, lines 9-22 (“[T]he purpose of the survey questions is to determine whether samples of potential jurors understood various aspects of jury instructions.... I believe it very clearly shows that the potential jurors that were surveyed were very divided and confused.”) (statement of Prof. Rossi). To belie the Magistrate Judge’s conclusion that the Zeisel studies in fact measure juror comprehension, respondents, based on the testimony of Professor Lavrakas, contend that the incorrect answers could represent miscomprehension of the written questions making up the questionnaire. Likewise, respondents postulate that the incorrect answers may stem from such factors as poor literacy, fatigue, boredom and frustration. When pressed on cross-examination, however, Lavrakas could not substantiate any of these alternate hypotheses. For example, when asked to identify any portion of the survey questions that was ambiguous or biased, Lavrakas was unable to do so. Transcript at 947, lines 2-21. In stark contradiction to Lavrakas' unsupported speculation, Free’s experts presented convincing evidence affirmatively ruling out each of respondents’ theories. Professor Zeisel testified that, in designing the questions with Bradford, he was very careful to ensure that they were “objective questions and could not be — would not bias the jurors in any direction.” Transcript at 85, lines 4-5. That the questions were clear and unbiased was corroborated by the testimony of Professors Diamond, Hans, Levi and Rossi. See Transcript at 249, 1149 (with the exception of question 1, they are “really quite clear and are certainly unbiased in their construction”) (statement of Prof. Diamond); Transcript at 136-155 (all but question 1 are clearly drafted and unbiased) (statement of Prof. Hans); Transcript at 602, line 11 (“the survey was written very clearly”) (statement of Prof. Levi); Transcript at 610, lines 6-9 (“This particular questionnaire is a very short questionnaire as questionnaires go. In my opinion, it’s very clearly written, with few ambiguities. There are no multiple parts or branching questions.”) (statement of Prof. Rossi). Respecting the possibility that fatigue contributed to the results, one would expect that under such circumstances the potential jurors would have scored better on earlier numbered questions. Transcript at 1153-54 (statement of Prof. Diamond). As the results did not deteriorate from earlier to later numbered questions, and in the absence of any evidence to the contrary, we can only conclude that fatigue played no role in the survey results. Finally, Free presented compelling evidence that the data were not skewed as a result of random guessing or inadvertence on the part of the survey participants. The survey itself includes multiple questions on three of the five issues sought to be measured, a valid method of ensuring internal consistency. Transcript at 138, 206, 638 (testimony of Profs. Hans and Rossi). Indeed, to test the notion that the survey respondents did not take the questions seriously and merely guessed in a random fashion, Professor Rossi calculated the expected distribution of correct answers which would result from random behavior and compared it to the actual distribution. Transcript at 620, lines 7-12. Professor Rossi concluded that “large numbers of people scor[ed] systematically lower that one would expect if they were engaged in a casual sort of random response behavior.” Transcript at 622, lines 1-3. Further, Professor Diamond concurred with Rossi’s interpretation of the data, asserting that “when we see these patterns here of clustering, that would be inconsistent with [random guessing].” Transcript at 1153, lines 19-20. As a final basis in support of their assertion that the Zeisel studies do not measure juror comprehension, respondents contend that Magistrate Judge Weisberg “apparently misunderstood [Lavrakas’] testimony regarding factor analysis and the Cronbach Alpha calculation he performed on the Zeis-el data.” Respondents’ Objections to Report and Recommendation at 8. We disagree. Both factor analysis and Cron-bach’s Alpha calculation are means of depicting patterns of consistency in correct and incorrect answers to the survey questions. One of the theoretical assumptions underlying these analyses, however, is that the data to be examined must be continuous as opposed to binary or dichotomous. Transcript at 774-76, 1176-86 (testimony of Prof. Rossi); Transcript at 1085-89 (testimony of Prof. Diamond); Transcript at 844, 865-66, 926, 1221-24 (testimony of Prof. Lavrakas). Further, it is undisputed that multi-dimensional questions reduce factorial consistency. Transcript at 929, lines 10-12 (statement of Prof. Lavrakas). As the Zeisel survey data are in fact binary and the questions are multi-dimensional, Magistrate Judge Weisberg properly concluded that neither factor analysis nor Cronbach’s Alpha calculation undermined the construct validity of the Zeisel studies. C. Generalization of Zeisel’s Results to Others Respondents’ attack on the reasonableness of applying the Zeisel survey results to persons other than the survey respondents is threefold. First, respondents contend that it is improper to draw conclusions about the universe sampled from, i.e., all eligible jurors in Cook County, because Free has not demonstrated the representativeness of the samples. Second, respondents argue that, assuming the samples were representative of all eligible Cook County jurors, Free was convicted and sentenced in DuPage County and generalization outside the relevant universe is inappropriate in this case. Finally, respondents maintain that the survey conditions did not approximate a real-world setting and, as such, the results provide no insight into the endeavors of the Free jury. We address each issue seriately. 1. Representativeness of Survey Sample As noted by respondents, general difficulties may arise when a researcher depends on limited data from samples to answer general questions about populations. It is axiomatic that samples ordinarily are not identical to the populations from which they come. Hence stems the concept of sampling error, i.e., the difference between a sample and its population. Further, samples themselves are variable. For instance, if we were to take two samples from the same population, the composition of those samples will differ, as will the results generated. Nonetheless, we can be reasonable assured that a sample is representative of its population if (1) it is obtained by a process of random sampling, and (2) it is sufficiently large. See Frederick J. Gravet-ter & Larry B. Wallnau, Statistics for the Behavioral Sciences 174, 201-03 (1985). That the survey samples were randomly selected is supported by the overwhelming weight of the evidence. A random sample is one in which each individual in the population has an equal chance of being selected. Fredrick J. Gravetter & Larry B. Wallnau, supra, at 174; see also Hans Zeisel, The Uniqueness of Survey Evi dence, 45 Cornell L.Q. 322, 327' (1960). Professor Zeisel testified that, to ensure a random .sample, he used actual jurors called to service at the Daley Center on the days that the surveys were administered. Transcript at 19, lines 10-13. Further, according to the uncontradicted testimony of attorney James Bailinson, the survey respondents were grouped by jury officials in the same manner as those jurors sent to courtrooms for actual jury service. Upon arriving at the Daley Center, the potential juror handed in her summons and pulled from a basket a folded up piece of paper which contained a panel number.. Transcript at 1045, lines 9-12 (statement of James Bailinson). Once the juror received her panel number, she waited in Room 1700 of the Daley Center until her panel number was called. Transcript at 1045, lines 16-21 (statement of James Bailinson). Zeisel and his assistants “were given jurors from the assignment room just as the judges would get in batches from there.” Transcript.at 23, lines 20-22 (statement of Prof. Zeisel). Such a random sampling procedure is not only representative, but appears to be as good a probability sample of potential Cook County jurors that could be designed. See Transcript at 23, lines 23-24 (statement of Prof. Zeisel). The law of large numbers states that the larger the sample size, the more probable that the sample mean will be close to the population mean. Fredrick J. Grávetter & Larry B. Wallnau, supra, at 202. After removing those jurors who did not meet the requirements of Witherspoon v. Illinois, 391 U.S. 510, 88 S.Ct. 1770, 20 L.Ed.2d 776 (1968), the April 1990 survey sample consisted of 96 potential jurors, and the January 1992 survey sample included 95. According to Professor Zeisel, any concern that the sample size was too small to be representative is allayed not only by computation of a confidence interval for each question, but also by the results of a split-half reliability analysis. Transcript at 36, lines 10-23. Zeisel essentially divided the samples from each survey into two halves as they arrived in seriatim and treated them as independent samples. As a comparison .of the answering patterns for the two half samples of each survey revealed that they were nearly identical, we can conclude, and respondents have not rebutted, that the sample sizes were sufficiently large to ensure that the samples were representative of the population. See Transcript at 37, lines 5-15 (statement of Prof. Zeisel); see also Transcript at 727, lines 4-5 (“I feel that the sample size is adequate to infer about the population at large.”) (statement of Prof. Rossi). 2. Generalization to DuPage County Jurors Based on demographic differences between the survey samples, the Free jury and the populations of Cook and DuPage Counties as to gender, age, education level and race, Professor Lavrakas opined that the results of the Zeisel surveys cannot be extrapolated to the Free jury, a group falling outside the surveyed population. However, assuming that such demographic differences in fact exist, Free has presented compelling evidence that these variables are irrelevant to jurors’ ability to comprehend the jury instructions. Respecting differences in educational level, Professor Hans testified that the survey data demonstrate “fairly high levels of mis-comprehension of the judicial instructions. And the kinds of educational differences that the researcher have discovered I don’t think could really influence that conclusion.” Transcript at 168, lines 2-6. Finding a uniform pattern of consistent failure to answer the questions correctly and fairly even dispersion across the types of answers with no Systematic subgroup scoring better or worse, Professor Rossi concluded that the Zeisel data can be applied to the Free jury with high levels of confidence. Transcript at 645-651. The opinions of Professors Hans and Rossi are bolstered by the results of an independent study conducted by Professor Diamond and Jonathan Casper. The Diamond-Casper study in part tested juror comprehension of the IPI instructions, finding a high rate of incorrect answers to questions concerning aggravating and mitigating factors. Significantly, the study accounted for differences in scores by college and noncollege graduates, showing that college graduates maintained a high rate of miscomprehension and that the margin of improvement associated with a college education was relatively small. Transcript at 308-310 (testimony of Prof. Diamond). Likewise, Free presented substantial evidence that gender plays no role in jurors’ comprehension of the instructions. See Transcript at 191, lines 6-10 (“So if our sample contained more women than were in Cook County or DuPage County, whatever, I would say, well, here is an instance where that’s not going to influence materially the results. Because there isn’t that link in advance between gender and comprehension levels.”) (statement of Prof. Hans); Transcript at 1125, lines 7-10 (“In terms of their probability of getting an answer correct or incorrect, there is no evidence from these data that would lead you to conclude that there is a difference [between men and women] in getting these questions right.”) (statement of Prof. Diamond). Further, based on his tabulation of the survey results by gender, Lavrakas conceded that there is “no consistent pattern- in women answering differently than men.” Transcript at 953, lines 6-7. Lavrakas’ speculation that age may affect comprehension is unsupported by the evidence adduced at the hearing. Indeed, Lavrakas “did not tabulate the survey data by age and agreed that he had no empirical evidence suggesting that older people would be better able to comprehend the jury instructions than younger people.” Report and Recommendation at 16; Transcript at 954-55 (testimony of Prof. Lavra-kas). To the contrary, Free’s expert witnesses testified that based on the survey data, there is no correlation between age and comprehension of the jury instructions. See, e.g., Transcript at 1080, lines 5-16 (“out of the 17 questions, older people were less accurate on average on eleven of them, and they were more accurate on six of them. Overall I would say ... there is no difference.”) (testimony of Prof. Diamond). Finally, regarding racial demographics, Professor Diamond discovered that, of white survey respondents, less than fifty percent answered correctly on twelve of seventeen questions, suggesting an extraordinarily high level of misunderstanding on each of the five measured issues. Transcript at 1081-83. As Free was tried by an all white jury, it follows that differences in racial composition are irrelevant to the issue of whether the Zeisel data may properly be applied to the Free jury. In any event, Professor Rossi testified that he could not detect a relationship between race and comprehension. Transcript at 1189-91. Further, Lavrakas “ultimately agreed that race as a variable was not important in determining comprehension level.” Report and Recommendation at 17; Transcript at 1225-1227. We are mindful of the possibility of a “Type II error,” that is failing to reject a false hypothesis. However, as explained by Professor Diamond, because a Type II error assumes a difference in effect that goes undetected, we can never know the probability that such an error is being made in concluding that the demographic differences in question are irrelevant to comprehension. Transcript at 1125-26. Professor Diamond continued to state that although it is “hypothetically” possible, “there is nothing in the data to support the notion that a Type II error is being made.” Transcript at 1126, lines 5-7. Accordingly, merely raising the possibility of a Type II error is insufficient on the part of respondents to rebut Free’s showing that no correlation exists between the various demographic differences and juror comprehension. As such, we agree with Magistrate Judge Weisberg’s conclusion that “if the same survey instruments were used with prospective jurors in the DuPage County Courthouse under conditions like those in the Daley Center surveys, it is reasonable to expect similar results showing substantial levels of misunderstanding of the IPI instructions and the capital sentencing instructions used in the Free case.” Report and Recommendation at 21. 3. Mundane Realism In support of their claim that the survey data may not be applied properly to the Free jury, respondents further argue that the Magistrate Judge “ignored Dr. Lavra-kas’ testimony on ‘mundane realism,’ that is, the extent to which the Zeisel survey conditions approximated the ‘real world.’ ” Respondents’ Objections to Report and Recommendation at 18. We begin with the observation that Professor Lavrakas admittedly is not an expert in juror comprehension, nor has he read any of the literature concerning jury research. See Transcript at 808-823 (voir dire of Prof. Lavrakas). As such, it is ironic that respondents challenge the substance of the testimony of Free’s experts solely on the basis of Lavra-kas’ speculation regarding issues of juror dynamics and comprehension. Nonetheless, Magistrate Judge Weisberg recognized that the Free jury differed from the Zeisel survey respondents in three important ways: [1] They made an actual life or death decision, [2] they deliberated as a group instead of separately answering written questionnaires and [3] they made their decision after a trial and sentencing hearing in which they heard aggravating and mitigating evidence and arguments by the prosecutor and Free’s attorney which discussed how the jury should decide on the sentence. Report and Recommendation at 21. Accordingly, it is incumbent upon this court to consider the likely impact of these differences in conditions upon juror comprehension despite the lack of any competent testimony offered by respondents on the matter. The gravamen of respondents’ first assertion is that because the Free jurors made an actual life or death decision they were more “motivated” than the survey respondents who were merely taking a pencil and paper test. Indeed, there is no dispute that the Free jurors likely were more “motivated” in determining if death was the most appropriate sentence. In other words, jurors asked to pass ultimate judgment over another’s life will no doubt participate in an inner conflict requiring them to balance personal notions of morality and their perceived obligations to the legal system. Such emotional turmoil clearly was not present in the Zeisel studies. As pointed out by Professor Zeisel, however, whether the jurors reached the “correct” result as a matter of personal morality and whether the jurors comprehended and followed the judicial instructions are two different questions, Transcript at 22-23 — the relevant issue for our purposes, and the issue designed to be studied by the Zeisel surveys, being the latter. Acknowledging the difference in emotional state between the Free jury and the survey respondents, Free’s experts testified that empirical research demonstrates that intensity and emotions eclipse the cognitive abilities necessary for comprehension of such complex instructions. See, e.g., Transcript at 441-42 (“One of the difficulties is that when people are emotionally overwrought — and I guess what you were trying to say is that they are heavily emotionally involved — it sometimes cuts against comprehension.... high emotional level interferes with comprehension.”) (testimony of Prof. Diamond); see also Loftus, Eyewitness Testimony (1979) (emotions and intensity impair cognitive functions) (cited below by Free’s experts). Further, Professor Diamond testified that the conditions afforded the survey respondents provided a superior environment for comprehension than did the conditions in Free, particularly because the survey respondents not only had the instructions read to them, but also had a written copy for reference while answering the survey questions. Transcript at 1146-47. In light the uncon-tradicted evidence, we concur in Magistrate Judge Weisberg’s conclusion that such factors as “motivation” and “emotion” do not enhance juror comprehension, and that the survey respondents did not participate in an actual life or death decision does not undermine the results of the Zeisel surveys as applied to the Free jury. Respecting the effect of deliberation and closing arguments upon juror comprehension, Magistrate Judge Weisberg found that “the evidence is not strong enough to rule out the possibility that comprehension among members of the Free jury on some key issues may have been substantially aided by hearing the evidence, the arguments of the attorneys and by the process of deliberation.” Report and Recommendation at 24. After a careful review of the testimony of Professors Zeisel, Transcript at 37-41, 91, Hans, Transcript at 156-166, 221-22, and Diamond, Transcript at 306-07, we agree that the effect of these factors can only be assessed in conjunction with an analysis of the issues on which a likelihood of misunderstanding is claimed. Accordingly, we will revisit these factors infra Section III of this opinion. D. Volatility Respondents maintain that a comparison of the 1992 survey results with the confidence intervals predicted on the basis of the 1990 survey demonstrates a mark of inconsistency or “volatility.” We disagree. More than one confidence interval was calculated on the basis of the 1990 survey. Professor Zeisel calculated 95% confidence intervals based on percentages of incorrect answers, while Professor Rossi calculated 99% confidence intervals based on percent^ ages of correct answers. Each eliminated those questions for which no correct answer existed (questions 1, 13, 14, 15 and 16), as well as question 6, which was not included in the 1990 results because of a typographical error. Comparing the 1992 results to the Zeisel intervals, “the 1992 results fell within the predicted confidence intervals for 3 questions, fell slightly outside (1% to 2%) for 2 questions, outside by 4% to 6% for 3 questions and outside by 9% to 12% for 2 questions.” Report and Recommendation at 17-18. “Using Rossi’s confidence intervals, the 1992 results fell within predicted confidence intervals for 3 questions, slightly outside for 1 question, outside by 5% to 8% for 5 questions, and outside by 12% for 1 question.” Id. at 18. As an empirical matter, we agree with Magistrate Judge Weisberg and Professor Rossi that the levels of deviation in the 1992 survey from the results predicted on the basis of the 1990 survey {i.e., the confidence intervals) are “modest.” Report and Recommendation at 18; Transcript at 763, lines 13-14 (testimony of Prof. Rossi). According to Professor Rossi, that the two surveys were not identical accounts for this modest deviation. Transcript at 770-73. Indeed, the predictive quality of the confidence interval rests on the assumption of identical surveys being given under identical conditions. In any event, the fact that both surveys, with few exceptions, depict very high levels of misunderstanding buttresses the Magistrate Judge’s conclusion that the surveys are valid and reliable. III. The Impact of the Zeisel Survey Results on Free In determining the impact of the Zeisel data on Grounds 5, 10 and 14 of Free’s petition for habeas relief, this court is guided by the holding in Boyde v. California, 494 U.S. 370, 380, 110 S.Ct. 1190, 1198, 108 L.Ed.2d 316 (1990), that when presented with a claim that a capital sentencing instruction is ambiguous and therefore subject to an erroneous interpretation, the relevant inquiry is whether there is a reasonable likelihood that the jury has applied the challenged instruction in a way that prevents the consideration of constitutionally relevant evidence. Although a defendant need not establish that the jury was more likely than not to have been impermissi-bly inhibited by the instruction, a capital sentencing proceeding is not inconsistent with the Eighth Amendment if there is only a possibility of such inhibition. With this standard in mind, we turn to consider the conclusions to be drawn from the Zeisel survey results respecting each of the measured aspects of juror comprehension. A. Existence of a Mitigating Factor Designed to test whether jurors believe they must agree unanimously on the existence of a mitigating factor before that factor can be considered by an individual juror, questions 4 and 5 of the Zeisel surveys provide as follows: 4. A juror decides that the fact that Mr. Wood was only 25 years of age when he committed the murder is a mitigating factor sufficient to preclude the death penalty. However the other eleven jurors disagree and insist that his age is not a mitigating factor. The one juror believes that she cannot consider a mitigating factor unless the entire jury agrees upon it and votes for the death penalty. She votes for the death penalty- 5. A juror decides that the fact that Mr. Woods was good to his family is a mitigating factor sufficient to preclude the death penalty. However, the other eleven jurors disagree. The other jurors insist that no juror should consider the defendant’s good relations with his family as a mitigating factor unless they all agree it is a mitigating factor. The one juror accepts this approach and votes for the death penalty. The state of the law is clear: instructions which a reasonable juror could interpret as allowing individual jurors to consider only mitigating factors that the jury unanimously find violate the Eighth Amendment. Mills v. Maryland, 486 U.S. 367, 384, 108 S.Ct. 1860, 1870, 100 L.Ed.2d 384 (1988); see also McKoy v. North Carolina, 494 U.S. 433, 435, 110 S.Ct. 1227, 1229, 108 L.Ed.2d 369 (1990). Accordingly, a response that the jurors in questions 4 and 5 followed the judicial instructions is incorrect. In the 1990 survey, 25% and 36.5% of the subjects respectively answered question 4 and 5 incorrectly. After substituting the actual Free instructions in the 1992 survey, 14.7% of the subjects answered question 4 incorrectly, while 30.5% answered question 5 incorrectly. Finding that the deliberative process, as well as the attorneys’ closing arguments, would have provided a jury with assistance on the matter, Magistrate Judge Weisberg concluded that Free failed to demonstrate “a reasonable likelihood that either jurors generally or the jurors in his case would have misunderstood the instructions as requiring unanimous agreement on the existence of mitigating factors, precluding individual jurors from considering relevant mitigating evidence.” Report and Recommendation at 30-31. Free strenuously objects to this conclusion. We begin our analysis by noting that to the extent that only one of the Free jurors (the absolute minimum according to the 1992 survey results) misunderstood the law, then this court would be compelled to conclude that “the jury [as a whole] has applied the challenged instruction in a way that prevents the consideration of constitutionally relevant evidence.” Boyde, 494 U.S. at 380, 110 S.Ct. at 1198. This repercussion follows from the fact that the law affords independent authority to consider mitigating factors and, as such, any one juror could preclude the imposition of the death penalty. Nonetheless, in order to demonstrate a reasonable likelihood that at least one juror misunderstood the instant point of law, Free bears the burden of demonstrating that neither deliberation nor the attorneys’ closing arguments would improve comprehension respecting the unanimity issue. In the instant context, we, like the Magistrate Judge, believe that Free has not carried this burden. Respecting the likely effect of the closing arguments, Free contends that the passages relied upon by the Magistrate Judge do not speak to the issue of unanimity, but rather on the weight to be given mitigating factors once established. Petitioner’s Objections to Report and Recommendation at 2-3. Indeed, it appears that this is the case for two of the three passages. First, Magistrate Judge Weisberg relied on defense counsel’s remarks that: There is no hung jury, so to speak, in a capital situation.... [Y]ou are going to receive instructions that tell you very explicitly that all of you must agree, right down to the last one, unanimously, that there are no mitigating factors, there is nothing here in James Free of a mitigating nature that reflect on the death penalty before you can say to the Court — and your determination is mandatory — “your honor, sentence him to death.” You all have to agree on that. Yet again, ladies and gentlemen, the other verdict form that you will receive says that we cannot unanimously agree. Sentencing Transcript at C8417-18 (emphasis supplied). When asked whether this specific text “might have helped the Free jury understand the instructions that they were to receive,” Professor Levi responded: Actually, it confused me as you were saying that — to hear what I thought was the defense attorney saying you are going to receive instructions that tell you very explicitly that all of you must agree that there are no mitigating factors. I mean, he takes a long time until he gets to something that undoes that. ... In other words, this sentence is confusing. Transcript at 591, lines 8-17. Putting aside the incongruity of the defense counsel speaking of “no mitigating factors,” it appears that this excerpt relates to the sufficiency of the evidence, not to the initial establishment of the mitigating factors. The second statement of Free’s counsel relied on by Magistrate Judge Weisberg provides as follows: Ladies and gentlemen, in the instructions you will find the statement that if one of you — just one of your twelve finds among all of this situation in the evidence that you have heard that the death sentence should not be imposed, if just one of you, the rest of you must respect that. You must. That’s the law. That person or persons or group of you doesn’t have to convince all of the others that the sentence not be imposed. Not at all. After your due deliberations, if just one, two or three of you say, “I’m sorry, I find in James Free, and his background and in the circumstances, and in the law, that I am given a mitigating factor that impresses me enough not to give the death penalty,” ladies and gentlemen, the rest of you must abide by that. And in signing the verdict that says you cannot unanimously agree you are not saying, “we agree with that person.” You are merely saying, “One of our twelve, or more, cannot impose it because that person finds in this situation, from his or her own mind, conscience, background, values, that it not be imposed.” Sentencing Transcript at C8418-19 (emphasis supplied). Arguably this passage, as did the previous remarks, speaks to the sufficiency of the evidence, as opposed to whether an individual juror may consider a mitigating factor that all jurors do not agree exists. Despite the ambiguities in the first two passages, however, the concluding statement of Free’s attorney sufficiently conveys the idea that an individual juror may consider a mitigating factor regardless of whether there is unanimity over its existence: I ask you now to go back and to search these [mitigating factors?] and to search yourself and your mind and your heart and your individuality, and I submit that when you do that ... that you will say, “There are mitigating factors, you are a person, I am not going to tell the court to sentence you to death.” If any one or more of you feel that the way the other should respect that and sign the verdict [stating that you cannot unanimously find that there are no mitigating factors sufficient to preclude the death penalty]. Sentencing Transcript at C8438-39 (emphasis supplied). The above quoted passage differs from the previous two statements of Free’s lawyer in two significant manners. First, the presence of the phrase “There are mitigating factors,” coupled with the absence of such expressions as “impresses me enough,” justifies an inference that the excerpt relates information helpful to the jury in the initial assessment of whether a mitigating factor exists. In other words, this statement, unlike the preceding two, expresses the power of the individual to find mitigating factors without conveying distracting ideas about the sufficiency of the evidence. Second, the text was the very last statement in the defense’s closing argument, and was immediately followed by the judicial instructions. That the passage was not buried in the middle of the argument makes it more likely that the jurors actually remembered and relied upon it during their deliberation. Cf. Transcript at 578, lines 8-15 (statements made “way before the end of all the arguments” are not likely to be remembered) (testimony of Prof. Levi). Likewise, we agree with Magistrate Judge Weisberg that deliberation most likely would improve a jury’s understanding with respect to this issue. Based on the confidence intervals calculated for questions 4 and 5, we can safely conclude that a majority of the Free jurors understood the concept prior to deliberation. Once the issue is raised in deliberation, a virtual likelihood if in fact some jurors are seeking to establish unanimity on the existence of a mitigating factor, it is reasonable to assume that the majority opinion will prevail. See Transcript at 39, lines 7-13 (For whatever reason, whether it be “a deeply ingrained respect for majority rule in a democratic society, or because of the thought where if more people think so than I, they must be right, or whether they just want to go home, ... the essence of the deliberative process [is] that the majority wins over the minority.”) (testimony of Prof. Zeisel). In sum, because Free has failed to demonstrate that neither deliberation nor the attorneys’ closing arguments would improve comprehension on the instant concept, we cannot conclude that there is a reasonable likelihood that any member of the Free jury interpreted the instructions as requiring unanimous agreement on the existence of mitigating factors. B. Non-Statutory Mitigating Factors The Eighth Amendment requires that a capital sentencing scheme place no restrictions on the type of mitigating circumstances that the sentencer can consider. Lockett v. Ohio, 438 U.S. 586, 604, 98 S.Ct. 2954, 2964-65, 57 L.Ed.2d 973 (1978). As such, the sentencer’s consideration should not be limited to statutorily reeog-nized mitigating circumstances. To test juror comprehension respecting this point of law, Professor Zeisel included in his surveys the following questions: 2. A juror is persuaded that the fact that Mr. Woods was good as