is the hausman test fe or re which statistical model is used for the hausman test? is hausman test valid what is the hausman test with or without covariates why reject the hausman test with re model hausman test with or without covariates hausman test with or without covariates why use hausman test hausman test for FE is the hausman test statistically significant what is the difference between re and hausman's test what is the hausman test used to evaluate which model is used to test for a null hypothesis why does hausman test reject the null hypothesis why does hausman test use re model why is the hausman test used hausman test vs fixed effects test what is the test hausman test used for is a hausman test null what is the hausman test used for