How do I calculate the significance test for a covariate by hand?
Significance tests are conducted as follows: 1) Fit a model with all covariates of interest; save loglikelihood as ‘loglik’ 2) For each covariate, fit the model with that covariate removed; save loglikelihood as ‘ll_beta_test’ (the rest of the steps are done for each covariate) 3) delta2ll = ( 2 * loglik ) – ( 2 * ll_beta_test ) 4) df = ( number of latent classes – 1 ) * ( number of groups ) OR, for binary regression, df = number of groups 5) Compute the CDF of a Chi-square distribution for the value ‘delta2ll’, with ‘df’ degrees of freedom. This is the p-vale for that covariate.
