Hi all
I have a problem when executing a 2-way ANOVA. Let's say I want to find out about the significance of factors "year" & "practice" regarding variable "work". When I execute a 2-way ANOVA without including the interaction effect ("year"*"practice"), both factors seem significant. However, when I add the interaction only "practice" turns out to be significant - I was expecting either "year" or the interaction be significant as well (Homogeneity was not rejected btw).
Anyway, can somebody point to a couple of references that have come across something like that? What is the "proper" way to confront this issue? Include the interaction in step A and since it's not significant remove it from the model and re-execute in step B? Which results should I trust?
Thank you in advance
Evan
Evangelos Kontopantelis
Research Associate in Statistics
National Primary Care Research & Development Centre
5th Floor, Williamson Building
University of Manchester
Oxford Road
Manchester
M13 9PL
016127-57646
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