1. AMMBR II Gerrit Rooks

2. Checking assumptions in logistic regression Hosmer & Lemeshow Residuals Multi-collinearity Cooks distance

3. Hosmer & Lemeshow Test divides sample in subgroups, checks whether difference between observed and predicted is about equal in these groups Test should not be significant (indicating no difference)

4. Hosmer & Lemeshow Average Probability In j th group

5. First logistic regression

6. Then postestimation command

7. Including interaction term helps

8. Multicollinearity

9. Residuals Residual = observed value – predicted value / square root of variation

10. Residuals

11. Inspect observations with large residuals (>2.5 a 3)

13. Cooks distance (< 1) Means square error Number of parameter Prediction for j from all observations Prediction for j for observations excluding observation i

16. To Stata Use apilog.dta Awards = dependent variable For Awards inspect frequency counts Recode Awards into binary variable Estimate a LR model using yr_rnd meals enroll as predictors

17. To Stata Inspect classification table Perform Hosmer & Lemeshow test Inspect standardized residuals Inspect cooks distance See if interaction effects improve fit

18. Is the Wald test an accurate test to the significance of coefficients in Logistic regression analysis? a)Yes, just like regression analysis. b)Yes, it is accurate, although a Likelihood ratio test is more efficient c)No, unlike regression analysis, the Wald test is biased, especially for relatively small coefficients. d)No, unlike regression analysis, the Wald test is biased, especially for relatively large coefficients.

19. Use LRtest to check the significance effect of the variable yr_rnd Use auto.dta (if not on your pc then) – use http://www.stata-press.com/data/r11/autohttp://www.stata-press.com/data/r11/auto Predict which car will be foreign, using weigth and mpg as predictors

20. Is the interaction between weigth and mpg significant? Tip: always center variable before making interactionvariable.

21. use http://www.stata-press.com/data/r11/choicehttp://www.stata-press.com/data/r11/choice Does income, gender or type of car (European, Japanese or American) predict whether a car will be bought (choice)?