How to: Two-way ANOVA. Repeated measures by row
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How to: Two-way ANOVA. Repeated measures by row |
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Two-way ANOVA, also called two-factor ANOVA, determines how a response is affected by two factors. For example, you might measure a response to three different drugs in both men and women. Drug treatment is one factor and gender is the other. Prism uses a unique way to enter data. You use rows and columns to designate the different groups (levels) of each factor. Each data set (column) represents a different level of one factor, and each row represents a different level of the other factor. You need to decide which factor is defined by rows, and which by columns. Your choice will not affect the ANOVA results, but the choice is important as it affects the appearance of graphs and the kinds of post tests Prism can compare. This page shows you how to enter and analyze data with repeated measurements placed on a single row. Use a different 'how to' page if you enter repeated measurements in a subcolumn. 1. Create a data table and enter data From the Welcome (or New Data Table and Graph) dialog, choose the Grouped tab. If you are not ready to enter your own data, chose to use sample data and choose: Two-way ANOVA data -- RM by rows. ("RM" means Repeated Measures). If you plan to enter your own data, it is important that you choose the subcolumn format correctly, for the maximum number of replicates you have. Since your data are repeated measures, you want to make a graph that shows that. Choose the fifth choice on the second row of graph types, so values are connected properly on the graph. If you choose sample data, Prism automatically chooses the appropriate graph.
Enter the data putting matched values in the same row, in corresponding columns. In the sample data shown below, the two circled values represent repeated measurements in one animal.
2. Choose two-way ANOVA
3. Interpret the results Interpreting results: Repeated measures two-way ANOVA Graphing tips: Repeated measures two-way ANOVA Checklist: Repeated measures two-way ANOVA
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