Minitab - Analysis of Variance - Two-way

For Version 17 of Minitab, go to this tutorial rather than using the present one (which will work better with prior versions).

The Minitab Worksheet is available. It contains the following data:

 Column N Comments IV1Code 10 Dummy codes for groups (1=0%EDC, 2=35%EDC). IV2Code 10 Dummy codes for groups (1=young, 2=older). TrialstoPA 10 Number trials to learn PA.

Since the Two-way analysis in Minitab does not give cell means, we need to get those first. Use the "Descriptive Statistics..." command off of the "Stat, Tables" menu. That is:

That will take you to the following dialog box:

For the "Catagorical variables:", type in (or double click on) the variables that code each IV. Type one in to the rows and one into the columns. Everything else should be blank. Then choose the "Associated Variables ..." button which will take you to the following dialog box.

In the box for "Associated variables:", choose the variable that contains the DV scores. Then check "Means" and "Standard deviations". Click on "OK" twice and you will see the following output.

 Tabulated Statistics: IV1Code, IV2Code Rows: IV1Code Columns: IV2Code          1      2    All 1    3.600  6.000  4.800      1.140  1.581  1.814          5      5     10 2   15.600  6.400 11.000      2.881  2.608  5.497          5      5     10 All  9.600  6.200  7.900      6.653  2.044  5.098         10     10     20 Cell Contents: trialstoPA : Mean                trialstoPA : Standard Deviation                             Count

It would be helpful to plot these means, but Minitab is not particularly friendly in this regard. For the analysis, use the "Two-way..." command off of the "Stat, ANOVA" menu. That is:

It will lead to the following dialog box:

Type (or click) in the "Response" (DV) variable as well as the variables containing the codes for each factor (i.e., "Row factor:" and "Column factor:" After clicking OK, the output will appear as follows:

 Two-way ANOVA: trialstoPA versus IV1Code, IV2Code Analysis of Variance for trialsto Source       DF      SS      MS      F      P IV1Code       1   192.2 192.200  40.68  0.000 IV2Code       1    57.8  57.800  12.23  0.003 Interaction   1   168.2 168.200  35.60  0.000 Error        16    75.6   4.725 Total        19   493.8 S = 2.174 R-Sq = 84.69% R-Sq(adj) = 81.82%