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remcarmi
Level I

Using a covariate in a factorial

Hi all, 

 

I have a data set where I am wanting to use initial body weight as a covariate for the subsequent body weights of the trial. However, when I use the covariate it changes my least square means. My question is why?  For example, my average end weight for one treatment without the covariate included is 1310.9, but when the covariate is included it changes to 1302.3.Shouldn't it only effect the other p-values? I have been including the covariate in the constructed model effects box. Is this the correct placement of my covariate? When the covariate is included my least square means values do not match up with my average daily gain values. When using the covariate, my daily gain shows to be 3.94, while my independent analysis of average daily gain are 4.03. 

1 REPLY 1

Re: Using a covariate in a factorial

Is the study design fully balanced?

 

May you share either the data or the JMP platform (results)?