ANCOVA post hocs?

[afairclo]

How do I do post hocs for ANCOVAs?

[TheEcologist]

How do I do post hocs for ANCOVAs?

A link that might be useful:
http://www.gigawiz.com/simplecomp.html


and if you per chance use SPSS:

http://bama.ua.edu/~jhartman/689/ancovaglm.ppt

[Dragan]

How do I do post hocs for ANCOVAs?

The analysis is done on the adjusted means. For a one-way ANCOVA with one covariate then it is as follows:

t= (YbarAdj(i) – YbarAdj(j)) / Sqrt [ MSw(adj) * (1/n(i) + 1/n(j)) + (Xbar(i) – Xbar(j))^2 / SSX(w) ]

where YbarAdj(i) is the adjusted mean of group i
MSw(adj) is the adjusted mean squares within from the overall analysis
Xbar(i) is the mean of the covariate for group i
SSX(w) is the sums of squares within associated with the covariate.
use t(df=N - #of groups - 1) as your critical value.