Collinearity, bias, and effect size: Modeling "the" effect of track on achievement

The estimated effect of any factor can be highly dependent on both the mode l and the data used for the analyses. This article presents an example of t he estimated effect of one factor in two different data sets under three di fferent forms of the standard linear model using the effect of track placem ent on achievement as an example. Some relative advantages and disadvantage s of each model are considered. The analyses demonstrate that, given collin earity among the predictor variables, a model with a poorer statistical fit may be useful for some interpretive purposes. (C) 1999 Academic Press.