Ruling Out Threats To Validity

The estimate-and-subtract methodfor eliminating threats to validity is described. Yeaton and Sechrest (1986, 1987b) argue that "no-difference"findings are fundamental to the process of eliminating threats to validity. The estimate-and-subtract method, however, eliminates a threat to validity without reliance on no-difference findings. This article argues that eliminating a threat to validity using the estimate-and-subtract method often is preferable to eliminating a threat to validity using no-difference findings. The article also shows how to improve the use of no-difference findings in those instances where their use is appropriate.