COMPONENTS OF ARTIFACTUAL VARIANCE IN META-ANALYTIC RESEARCH

Except for a few rough estimates, the literature contains no precise data on the relative size of each correctable artifact in a meta-analysis. The purpose of the present study was to determine these proportions and see if artifacts were related to various sample and subpopulation parameters. The study confirmed the notion that sampling error accounts for the bulk of the total artifactual variance (i.e., more than 90% for small or medium samples and more than 70% for large samples, e.g., N = 500). Nevertheless, variation in the percentages of each artifact was found to be primarily a function of sample size and mean correlation. Total artifactual variance was found to be a function of subpopulation correlation differences and sample size. Practical implications of the results are presented.     

DETECTING MODERATORS WITH META-ANALYSIS: AN EVALUATION AND COMPARISON OF TECHNIQUES

The present study evaluated accuracy levels of seven techniques for ascertaining, after a meta-analysis, whether moderators are present or not: (a) SH-75% rule for uncorrected r , (b) SH-75% rule for corrected r, (c) SH-95% rule for uncorrected r , (d) SH-95% rule for corrected r, (e) the Q statistic; (f) inclusion of 0 in the credibility interval around the corrected r, and (g) the size of the interval. Using Monte Carlo data which were defined by various parameters including sample based artifacts, comparisons of Type I and power determinations were generated. Findings showed that when differences between population correlations were small, power levels for all techniques were relatively low. Overall, SH rules and the Q statistic had greater power but higher Type I error rate than credibility intervals. Because of the high Type I error rate associated with both of the SH-95% techniques and the low power found with the credibility intervals, the SH-75% rules and Q statistic are recommended. Limitations and some practical implications for the findings are discussed.     

Specific and Generic Objects in Cavell and Thomas Aquinas

Here I establish a parallel between modern epistemology and traditional metaphysics: between the way we know an object, on the one hand, and the way an object's causes cause it to exist, on the other. I show that different efficient causes in the Thomistic system correspond to different questions of knowledge, as analyzed by Stanley Cavell, and that in particular the question the Cavellian skeptic asks corresponds to God's causation in creation. As I have explained in detail elsewhere, and discuss briefly here, this parallel represents far more than a formal analogy between a series of issues in epistemology and a series of issues in metaphysics. It helps to explain, in fact, why modern philosophers (e.g., Husserl) were ultimately driven to put the human ego in the place of God, as creating (or "positing") the objects of its knowledge, thereby denying the very distinction between epistemology and ontology.