JASP: DFs for ANCOVA with within-subjects design

Comments

• RaviSelker

  February 2016 edited 1:35AM

  Hi Tom,

  JASP only allows repeated measures data in wide format. Your data is in long format (for the difference, see http://www.theanalysisfactor.com/wide-and-long-data/), so you must reformat the data in order to use it in JASP. Subsequently, to run the mixed ANCOVA you need to select the repeated measures ANOVA in JASP (not the ANCOVA). The following website gives a clear, step-by-step description of how to setup your analysis in JASP (under JASP: Using the Software): http://www4.uwsp.edu/psych/cw/statistics/textbook.htm.

  Cheers,
  Ravi
• tomstafford

  February 2016 edited 1:35AM

  Thanks Ravi - that is absolutely clear and useful
• coledavis

  May 2016 edited 1:35AM

  I've converted a repeated measures file to wide format, but keep getting a message from JASP ANCOVA that "Singular fit encountered; one or more predictor variables are a linear combination of other predictor variables".

  Temporarily, on www.coledavis.org/test you will find the original repeated measures ANOVA csv file and the new 'wide format' ANCOVA csv file. Can you tell me what I've done wrong?
• RaviSelker

  May 2016 edited 1:35AM

  Are you doing the analysis on the "ThreeWayRepeatANOVA.csv" data set? Because that is the one that you should use in JASP as this is in wide format. The "Ancova.csv" is in long format. If I try the analysis I assume you want to do (I assume you want to do a 322 RM ANOVA) using the "ThreeWayRepeatANOVA.csv" data set it seems to work.
• coledavis

  May 2016 edited 1:35AM

  No, the ThreeWayRepeatANOVA.csv is only there to show you the original data, which does as you say work on ANOVA. The information in this was converted into long format for the purposes of ANCOVA. If you try out the ANCOVA.csv data on JASP's ANCOVA test, you should see the error message I reported.
• coledavis

  May 2016 edited 1:35AM

  Perhaps you could send me what you deem to be a satisfactory data set which represents a repeated measures set for ANCOVA and a between-subjects data set which would be satisfactory for ANCOVA?
• coledavis

  May 2016 edited 1:35AM

  Ah, I have just done some more reading. Really, ANCOVA shouldn't be used for Repeated Measures, requiring independent error terms. So, not really relevant. Sorry again.