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GRA 6020 Multivariate Statistics; The Logit Model Introduction to Multilevel Models. Ulf H. Olsson Professor of Statistics. The Logit Model. The Logistic Function e ~ 2.7 1828 1828. The Logit Model. Logit Model for P i. Binary Response Models.
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GRA 6020Multivariate Statistics; The Logit ModelIntroduction to Multilevel Models Ulf H. Olsson Professor of Statistics
The Logit Model • The Logistic Function • e ~ 2.7 1828 1828 Ulf H. Olsson
The Logit Model Ulf H. Olsson
Logit Model for Pi Ulf H. Olsson
Binary Response Models • The magnitude of each effect is not especially useful since y* rarely has a well-defined unit of measurement. • But, it is possible to find the partial effects on the probabilities by partial derivatives. • We are interested in significance and directions (positive or negative) • To find the partial effects of roughly continuous variables on the response probability: Ulf H. Olsson
The Marginal effect Ulf H. Olsson
Simple interaction Model; X-continuous and D dichotomous Ulf H. Olsson
The Logit Model • Non-linear => Non-linear Estimation =>ML • Model can be tested, but R-sq. does not work. Some pseudo R.sq. have been proposed. • Estimate a model to predict the probability Ulf H. Olsson
Introduction to the ML-estimator Ulf H. Olsson
Introduction to the ML-estimator • The value of the parameters that maximizes this function are the maximum likelihood estimates • Since the logarithm is a monotonic function, the values that maximizes L are the same as those that minimizes ln L Ulf H. Olsson
Goodness of Fit The lower the better (0 – perfect fit) Some Pseudo R-sq. The Wald test for the individual parameters Ulf H. Olsson
Multilevel Models More general than panel models
School Pupil School Neighbourhood Pupil Classifying Structures Simple hierarchy Cross classifications Multiple membership Ulf H. Olsson
Simple panel model Studying nine individuals and five time periodes; i= 1,2,..,9. t= 1,..,5; Y: Wages; X:Education level Ulf H. Olsson