ERIC Number: ED357068
Record Type: Non-Journal
Publication Date: 1993-Apr
Reference Count: N/A
An F-Enhanced Stagewise Protected Procedure for Testing a Complete Set of Planned Orthogonal Contrasts.
Klockars, Alan J.; Hancock, Gregory R.
The challenge of multiple comparisons is to maximize the power for answering specific research questions, while still maintaining control over the rate of Type I error. Several multiple comparison procedures have been suggested to meet this challenge. The stagewise protected procedure (SPP) of A. J. Klockars and G. R. Hancock tests null hypotheses sequentially, with each stage of testing preceded by an omnibus F-test on the remaining between-group variability. A modification of this SPP is proposed and tested through a Monte Carlo simulation. A redirection of the Type I error rate in protected tests is proposed to be an indirect reference to the probability that both the omnibus and contrast null hypotheses will be rejected. Simulation results indicate that the proposed adjustment of the alpha-level for the stagewise omnibus F-tests appears to provide the needed power to the original SPP where it was previously weak, and does so without increasing the Type I error rate for the experiment beyond the nominal alpha-level. Two tables present analysis results. (SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Authoring Institution: N/A