Nonrandom assignment and the analysis of covariance in aging research.
A technique developed initially by Overall and Woodward for using nonrandom assignment in ANCOVA is reviewed. Though such a technique produces unbiased measures of treatment effects, this is only true when the assumptions of ANCOVA have been met and when group assignment is based on covariate scores. Limitations and potential applications for such a technique in gerontological research are reviewed.
D000368:Aged; D000375:Aging; D000704:Analysis of Variance; D006801:Humans; D012107:Research Design; D013223:Statistics as Topic