Beauchamp:ANOVAs in MATLAB

While all of your data may be in Excel, unfortunately, the Excel for Mac doesn't do ANOVAs.

So, let's use MATLAB! In this example, I'm doing a 2x2 ANOVA on the BOLD amplitudes of response in the right STS (dependent measure).

The two factors are perceiver group (strong McGurk perceivers: 1 and non-perceivers: 2) and stimulus condition (McGurk: 1, non-McGurk incongruent: 2, and congruent: 3).

I'd like to know if there is a significant difference in the right STS response between the different the subjects who did and did not perceive the McGurk effect, between the responses to the 3 different stimuli, and if there is an interaction between perceiver group and stimulus type.

The data for the dependent measure and each factor are put into columns in Excel.

R_STS	PerceiverGroup	StimulusType				
0.1662	1	1				

0.0467 1 1 0.1364 1 1 -0.0025 1 1 0.0185 1 1 0.1162 1 1 0.1935 1 1 0.2685 2 1 0.0704 2 1 0.3541 2 1 0.1392 2 1 0.2367 2 1 0.0507 2 1 -0.0558 2 1 0.0738 2 1 0.0473 2 1 0.0119 2 1 0.1375 1 2 0.1354 1 2 0.1931 1 2 -0.26 1 2 0.0425 1 2 0.2904 1 2 0.3069 1 2 0.4702 2 2 -0.0295 2 2 0.391 2 2 0.2323 2 2 0.6401 2 2 0.0562 2 2 0.0488 2 2 0.0567 2 2 0.0635 2 2 -0.0592 2 2 0.1264 1 3 0.1002 1 3 0.1368 1 3 -0.0933 1 3 0.0391 1 3 0.2585 1 3 0.1405 1 3 -0.002 2 3 0.0307 2 3 0.1367 2 3 0.2007 2 3 0.438 2 3 0.0782 2 3 0.0595 2 3 0.0279 2 3 -0.0203 2 3 -0.0746 2 3

Then, I copied the data from each into a array in MATLAB with the same name.

Then, run the function 'anovan.m' in MATLAB:

    anovan(R_STS,{PerceiverGroup StimulusType},'model',2,'varnames',strvcat('Group','Stim'))					

The output is a chart-- copy it back into your Excel spreadsheet to have the numbers handy.

    Source Sum Sq. d.f. Mean Sq. F Prob>F					
    --------------------------------------------------------					
    Group 0.00787 1 0.00787 0.3 0.5848					
    Stim 0.03208 2 0.01604 0.62 0.544					
    Group*Stim 0.01316 2 0.00658 0.25 0.7775					
    Error 1.1696 45 0.02599					
    Total 1.2314 50