Topics: Specification of the 2PL-Birnbaum model in Mplus for the life satisfaction data, Test of the hypothesis: „The Rasch model holds“ using the Wald test, Specification of the 2PL-Birnbaum model in Mplus for generated data that follow the Birnbaum model, Test of the hypothesis: „The Rasch model holds“ using the Wald test for these data that follow the Birnbaum model