ERIC Number: ED393916
Record Type: RIE
Publication Date: 1996-Jan
Reference Count: N/A
The Use of Planned Comparisons in Analysis of Variance Research.
This paper briefly describes unplanned and planned methods of evaluating differences between means and explains orthogonal versus nonorthogonal contrasts to help the researcher understand a framework of planned comparisons. A small heuristic data set is generated to illustrate the superiority of planned comparisons over omnibus analysis of variance (ANOVA) testing and to compare nontrend orthogonal contrasts and nonorthogonal contrasts. The hypothetical data set is used to show that planned comparisons can detect a significant difference between means or a pair of means while a classical test of variance fails to find any statistical significance. Methodologically, planned comparisons have important advantages over unplanned or post hoc tests when the researcher has theoretical ground for focusing on a particular hypothesis or hypotheses. Researchers need to think about the research topic thoughtfully before they choose an omnibus ANOVA test. When they are not certain of the comparisons they wish to make, omnibus ANOVA tests would be applied. (Contains 1 figure, 5 tables, and 16 reference.) (SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Authoring Institution: N/A
Identifiers: Omnibus Tests; Orthogonal Comparison; Planned Comparisons; Post Hoc Tests
Note: Paper presented at the Annual Meeting of the Southwest Educational Research Association (New Orleans, LA, January 1996).