The Misuse of ANCOVA: The Academic and Political Implications of Type VI Errors in Studies of Achievement and Socioeconomic Status

Abstract

This paper examines ANCOVA designs which use SES as the covariate for achievement and Type VI errors. Type VI errors are inconsistencies between the research question and the research methodology, and these errors are discussed in the context of general semantics. The consequences of a Type VI error in studies of achievement differences covariating for SES can be highly misleading. When research with a Type VI error concludes that there are no significant differences in achievement across groups when
statistically controlling for SES, the tacit implications are that actual achievement is consistent across groups and that SES can be causally controlled or is somehow not influential. Neither is correct. Authors suggest conducting validity studies of adjusted outcome scores to insure accuracy in interpreting results.