Open LGraz opened 4 days ago
Dear @LGraz ,
Thanks for taking the initiative to add this functionality. Yes, I am interested in a PR that implements this. It would be great if the PR could include a few simple tests that help to ensure that things keep working.
Best, Manuel
Dear @kollerma
I am currently implementing my own way how to get sensible p-values for an
rlmerMod
model and I would like to share it with the world.lmerTest
uses the contest / contestMD / contest1D functions to get their p-values. Then all contrasts and ANOVAs (= simultaneous contrasts) are performed in the aforementioned functions and testing against 0.Since I don't think we can work with the classic sums of squares, I have implemented a test, that using the Hotelling t-squared statistic and a contrast matrix $K$, tests the nullhypothethis : $K \times fixef(fit) = 0$ by computing the test-statistic
t(K %*% fixef(fit)) %*% solve(K %*% vcov(fit) %*%K ) %*% K %*% fixef(fit)
which under the null follows the distribution $\frac{p * (n - 1)}{n - p}F_{p, n - p}$.I have tested this approach for the sleepstudy data, simulating under the null. Using my ANOVA method, I got a .95 correlation with
anova.lmerModLmerTest
and in an unbalanced case it is slightly more conservative.Would you be interested in a PR? Or should I publish this separately?