Return the results of a score test for a linear constraint.
See also GEE.compare_score_test for an alternative way to perform a score test. GEEResults.score_test is more general, in that it supports testing arbitrary linear equality constraints. However GEE.compare_score_test might be easier to use when comparing two explicit models.
Xu Guo and Wei Pan (2002). “Small sample performance of the score test in GEE”. http://www.sph.umn.edu/faculty1/wp-content/uploads/2012/11/rr2002-013.pdf