Hello there,
I am using the robumeta package in R to fit a meta - regression model.
One of my categorical moderators has three levels. Everything is dummy coded.
AFAIK regression coefficients robumeta gives out indicates whether there is a difference between a single level of a moderator and a single comparison level. No problem with categorial moderators with only two levels. But not really helpful for a categorical moderator with 3 levels To create an omnibus test and get an F that indicates whether the moderator as a whole is significant, Tanner & Smith (2016) suggested using the club sandwich package.
I have read through the tutorial and the package descriptions, but I assume my knowledge about Wald-Tests is lacking. In the tutorial I am reading they use different constraints like 2:3. / 2:4 / 2:6.
Can someone explain to me what constraints to use / how to choose the constraints?
R fitted model looks as follows (Occupation being the moderator with three levels):
Fit