Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2 Meta-analysis of Forcad-Choice Precognition Experiments 6 CTE, AR antepee OVERALL CUMULATION Evidence for overall directional hitting and for successful prediction of hitting and missing tendencies is strong.? As shown in the top part of Table 1, the overall results are highly significant. The mean predicted z is twice as large as the mean directional z, indicating the advantage of making focused predictions (and the lawfulness implied by being able to do so). Thirty percent of the studies show overall significant hitting at the 5% level. Nearly 40% are significant on the basis of the investigators’ predictions. TABLE 1; Overall Precognition Significance Levels Zdir Zpred Mean 0.69 1.38 Standard Deviation 2.65 2.36 Combined (Stouffer) z 12.14 24.23 P, 6x10?” 4x10> Filedrawer Estimate 16,529 66,687 Lower 95% Confidence Estimate 0.44 1.16 Lower 99% Confidence Estimate 0.34 1.07 Lower 99.9% Confidence Estimate 0.22 0.97 Lower-bound confidence estimates of the mean z-scores displayed in the bottom portion of Table 1 indicate that the mean directional and predicted z-scores are well above zero at the 95%, 99%, and 99.9% confidence levels. Significance levels, not surprisingly, are related to sample size. The correlation (7) is 0.151 for the directional z’s (307 df, p = .0044), and for the ‘The statistical analyses presented here were performed using SYSTAT (Wilkinson, 1988). When t-tests are reported on samples with unequal variances, they are calculated using the separate variances within groups for the error and degrees of freedom following Brownlee (1965). Unless otherwise specified, p-levels are one-tailed. Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2
Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2 Meta-analysis of Forced-Choice Precognition Experiments 7 eS ee predicted z’s, r is 0.242 (307 df, p = 8.4.x 10°). Directionally significant Studies have a mean sample size that is 37% larger than the mean for directionally nonsignificant studies. Using the predicted z-score criterion, significant studies have a mean sample size that is more than double that of the nonsignificant studies. The effect size analysis is presented in Table 2. Both directional and predicted outcomes are significantly above zero, and again, the mean predicted effect size is twice as large as the directional mean ES. TABLE 2: Overall Effect Sizes eee a Mean 0.022 0.041 Standard Deviation 0.098 0.092 £(308) 4.01 7.88 pt 4x10° 3x10 Lower 95% Confidence Limit 0.012 0.032 Lower 99% Confidence Limit 0.008 0.029 Lower 99.9% Confidence Limit 0.005 0.025 A SS pt si esi SSFP Replication across Investigators Virtually the same picture emerges when the cumulation is by investigator rather than study as the unit of analysis. The combined z’s are 12.71 for directional outcomes and 22.12 for predicted outcomes. Twenty-four of the 62 investigators (39%) have directional outcomes significant at the 5% level, and 39 investigators (63%) have significant predicted outcomes. The mean (investigator) directional effect size is 0.036 (sd = .091), and the mean predicted ES is 0.050 (sd = .087). These results indicate a substantial level of cross-investigator replicability and directly contradict the claim of critics such as Akers (1988) that Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2