ANOVAinSPSS[1]

How to do a Two-Way ANOVA in SPSS In order to run a two-way ANOVA in SPSS , the data need to be arranged a certain way. Each subject has his/her own row, with information about indep endent variables and dependent variables in the columns. To do the exercises on the following pages, you will need to open an empty data spreadsheet in SPSS. First, enter the values for the dependent variable in one co lumn. You can label this column by clicking on the tab at the bottom of the window labeled “variable v iew”. Then click back to “data view”. In the sec ond column, enter information about the first Independent Variable (the first factor) by assigning names or numbers to each level (or group) and typing the appropriate level for each participant (row) in the appropriate box in the column. Next enter the second Independent Variable in a third column by assigning names or numbers to its levels and entering the appropriate level in the appropriate box for each participant (row). Depending on which data set you were working with, your spreadsheet start with something like the following: subj IV1 IV2 depv 1 Male Exper 5 2 Male Exper 5.5 3 Male Control 6 4 Male Control 4.7 5 Female Exper 9 6 Female Exper 6.2 7 Female Control 5.3 Running the analysis Running a Two Way ANOVA When we run a one-way ANOVA, we used a special menu command for that type of analysis (as you'll see below). But since one can have a broad range of factors in an ANOVA, SPSS has a more general menu command that allows you to do all kinds of ANOVAs (one-way, two-way, three-way, etc.). Click on ANALYZE -> GENERAL LINEAR MODEL -> UNIVARIATE, The dependent box is for the dep endent (continuous) variable that you want to analyze. The “Fixed factor” box is for the set of factors (groups) you want to look at. Move the DV into the DV box, using the little arrow button between the fields Move the 1st IV into the Fixed factor box. Move the 2nd IV into the Fixed factor box. Click “ok” and you’ll get your two-way ANOVA table. If you only put one factor into the box, you’d get a one-way ANOVA. If you put in three factors, you’d get a three-way ANOVA. You get the picture. Comparing Individual Means To get SPSS to print out information about the means of the cells, click on the “Options” button in the univariate model window. In the menu that opens, indicate that you want SPSS to display the means for the two factors and their interaction. If you want to run multiple comparison tes ts on the means, check the “compare main effects” box and indicate what type of multiple comparison you want (LSD, Bonferroni, etc.). Then click “continue” to get back to the univariate model wind ow. When you run the analysis, the information about the means will be printed below the ANOVA table. Graphing instructions To get SPSS to print out a grap h of the means, click on the “Profile Plo ts” button in the univariate model window. In the menu that opens, indicate that you want to use one IV as the firs t grouping variable on the horizontal axis. Indicate that you want to use the second IV as he second grouping variable, plotted as separate lines. Click “continue” and, when you run your analysis, the graph will be printed below the ANOVA table. You can create a second graph from the same data by switching which IV is on the horizontal axis and which IV determines the separate lines. Remember, if the two (or more) lines are parallel there is no interaction between them (no interaction effect) – they do not need to cross over to have an interaction. The different (separate) lines represent the levels/conditions/groups of one of your IVs, while the points on the X-axis represent the levels/conditions/groups of the other IV.

ANOVAinSPSS[1]

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