ranova with two within factors

64 views (last 30 days)
Rose Potter
Rose Potter on 15 Jun 2019
Commented: Jeff Miller on 23 Apr 2021
Hello everyone,
I have a question about how to do a repeated measures anova in Matlab. I have data from 20 people who were tested in 4 conditions each: treatment A pre test, treatment A post test, treatment B pre test, treatment B post test. I want to use time and treatment as factors. However I only managed an anova with one factor. Here's what I got so far:
datatable = cell2table(struct2cell([pre.A, pre.B, post.A, post.B]'));
datatable.Properties.VariableNames = {'pre_A','pre_B','post_A','post_B'};
rm = fitrm(datatable, 'pre_A,pre_B,post_A,post_B~1','WithinDesign',[1:4]);
ranovatable = ranova(rm)
How do I introduce the treatment as a second within factor? I read the documentation but did not find anything I could make use of. Thank you so much in advance!

Accepted Answer

Jeff Miller
Jeff Miller on 16 Jun 2019
Edited: Jeff Miller on 24 Nov 2020
datatable.Properties.VariableNames = {'pre_A','pre_B','post_A','post_B'};
% When you have more than one repeated-measures factor, you must set up a table
% to indicate the levels on each factor for each of your different variables.
% Here is the command you need for this case:
WithinStructure = table([1 1 2 2]',[1 2 1 2]','VariableNames',{'PrePost','TreatAB'});
% The 4 different rows of the WithinStructure table correspond to the 4 different
% columns, 'pre_A','pre_B','post_A','post_B', respectively, in your data table.
% Each 'pre_A','pre_B','post_A','post_B' column is coded as 1/2 on the PrePost factor
% and as 1/2 on the TreatAB factor.
% (Added based on later comments:)
% Indicate that the 1's and 2's of WithinStructure are category labels
% rather than regression-type numerical covariates:
WithinStructure.PrePost = categorical(WithinStructure.PrePost);
WithinStructure.TreatAB = categorical(WithinStructure.TreatAB);
% Now pass the WithinStructure table to fitrm so that it knows how the different
% columns correspond to the different levels of the repeated-measures factors.
rm = fitrm(datatable, 'pre_A,pre_B,post_A,post_B~1','WithinDesign',WithinStructure);
% Finally, you need to specify the repeated-measures factors again when you call ranova, like this:
ranovatable = ranova(rm,'WithinModel','PrePost*TreatAB');
  10 Comments
Jeff Miller
Jeff Miller on 23 Apr 2021
No, sorry, I can't tell from this info. I suggest you start a new question and provide more explanation about the design, as well as all the relevant code.

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!