The case for preferring analysis of covariance (ANCOVA) to the simple analysis of change scores (SACS) has often been made. Nevertheless, claims continue to be made that analysis of covariance is biased if the groups are not equal at baseline. If the required equality were in expectation only, this would permit the use of ANCOVA in randomized clinical trials but not in observational studies. Th...

Despite numerous technical treatments in many venues, analysis of covariance (ANCOVA) remains a widely misused approach to dealing with substantive group differences on potential covariates, particularly in psychopathology research. Published articles reach unfounded conclusions, and some statistics texts neglect the issue. The problem with ANCOVA in such cases is reviewed. In many cases, there...

The authors compared the performance of 78 African American 5th-grade students who studied a math-estimation task in one of two learning contexts. Learning contexts differed in the degree to which they afforded the expression of communalism. ANCOVA confirmed that posttest performance was best for students who studied in the high communal-learning context. The findings support A. W. Boykin's (19...

_____________________________________________________________________________ The purpose of the study was to investigate the effect of endurance training methods on hemoglobin level of women athletes. The subjects were from the C.S.J.M University, Kanpur. The female students acted as the source of data. 20 female athletes of department of Physical Education, C.S.J.M University, Kanpur were sel...

There is a longstanding debate on whether the analysis of covariance (ANCOVA) or change score approach more appropriate when analyzing non-experimental longitudinal data. In this article, we use structural modeling perspective to clarify that ANCOVA based assumption all relevant covariates are measured (i.e., sufficient remove confounding) and provides biased estimates treatment effect in prese...

The aim of the present study was to investigate whether low levels of mono-ortho PCB 118 and di-ortho PCB 153, affect bone composition and strength in ewes (Dala breed) and their foetuses following exposure starting at conception and ending a week before expected delivery. In male foetuses, trabecular bone mineral content at the metaphysis was almost 30% lower in the PCB 118 (49 microg/kg body ...

BACKGROUND Analysis of variance (ANOVA), change-score analysis (CSA) and analysis of covariance (ANCOVA) respond differently to baseline imbalance in randomized controlled trials. However, no empirical studies appear to have quantified the differential bias and precision of estimates derived from these methods of analysis, and their relative statistical power, in relation to combinations of lev...

BACKGROUND Although seemingly straightforward, the statistical comparison of a continuous variable in a randomized controlled trial that has both a pre- and posttreatment score presents an interesting challenge for trialists. We present here empirical application of four statistical methods (posttreatment scores with analysis of variance, analysis of covariance, change in scores, and percent ch...