Two-way ANOVA with and without repeated measurements, tests of simple main effects, and multiple comparisons for microcomputers

Abstract

ENTER '0' FOR A OR B TO RETURN TO MENU COMPARE WHICH CELL (A,B)? I, I WITH WHICH CELL (A,B)? 1,3. ENTER '0' FOR A OR B TO RETURN TO MENU COMPARE WHICH CELL (A,B)? I, I WITH WHICH CELL (A,B)? 1,4 Manyexcellent programs to perform factorialanalyses of variance (ANOVAs) are available to microcomputer users (Collani & Waloszek, 1983; Corrigan, Bonelli, & Borys, 1980a, 1980b; Coulombe, 1983; Galla, 1981; Hacker & Angiolillo-Bent, 1981; Lane, 1981). Most of these can be used for the analysis of a variety of designs with equal or unequal numbers of subjects per cell. Only one of the above-mentioned packages allows for multiple comparisons with user-defined contrasts (Hacker & Angiolillo-Bent, 1981). None can perform tests of simple main effects when there are significant interactions in factorial designs. The purpose of the programs described here is to fully analyze experimental data derived from two-factor designs with or without repeated measures. A full analysis should include not only the ANOVA table and a listing of the marginal and cell means, but also tests of simple main effects when the interaction is significant, multiple comparisons on marginal means for both factors, and multiple comparisons on cell means. The present package includes three separate programs to perform two-way analysis of variance with no repeated measurements, or repeated measurements over one or two factors. Each programcan be run on a microcomputer with a minimum of 16K memory (RAM). The computational procedures used are described in Kirk (1968) and Winer (1971). Input. Each program starts by requestingthe number of levels for factor A and factor B. If independent samples are analyzed, the program (AOV2W) asks for the number of subjects in each cell (Ns can be unequal) and then accepts sequential entry of each score. If the analysis involves repeated measurements over one factor, the program (AOV2WRM1) requests the number of subjects in each level of factor A (the between factor). If the Ns are unequal, then the user is provided with the choice of using either an unweighted-means or a least-squares solution. Then each score is entered sequentially. Finally, if the design is completely crossed (repeated measurements over two factors), the program (AOV2WRM2) asks for the number of replications and proceedswith sequential entry of each score. Output. A sample output of the AOV2WRMl program is presented in Table 1. The outputs of the other programs follow a similar pattern. Each program output