Re: st: anova account for the same individuals

["Airey, David C" <david.airey@vanderbilt.edu>]

.

If you choose to use ANOVA for the omnibus test, you can follow up with paired t-tests as the posthoc test for pairwise comparisons of ads.

Be sure to say what version of Stata you have, because this allows advice on use of margins or contrast commands. You mention a tukeyhsd command that is not official Stata.

While you could also investigate other commands like manova, xtgee, xtmixed, or xtologit, if you don't have a lot of statistical support near you, careful use of graphs combined with anova and posthoc paired t-tests is probably OK. 

> Dear David,
> 
> Thank you very much for your response to my inquiry. For this two-way analysis of variance, can I run pairwise comparisons to test the difference in rating scores between two ads, e.g., tukeyhsd? How do I specify this in the post-hoc test?
> The scale of values for the rating scores is a 5-point Likert scale, ranging from 1 to 5. Indeed, this scale was created from 5 variables with values ranging from 1-5.  If the values are too few to run ANOVA, which method would be appropriate, xtmixed?
> Thanks,
> 
> Liling




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