17. In order for an instrumental variable to be valid, it needs to be: A) relevant B) irrelevant C) binary D) continuous 18. Instrumental variable Z is "weak" if: A) there is a very strong correlation between Z and X B) there is no correlation between Z and Y C) the first-stage regression yields an F-statistic less than 10. D) the correlation coefficient between Z and X is above 0.5. 19. Which of the following is the most appropriate to use as an instrumental variable: A) Educational attainment B) Interest rates C) Migration patterns D) Weather[Questions 1-4] In Ability, Gender, and Performance Standards: Evidence from Academic Probation, Jason M. Lindo, Nicholas J. Sanders, and Philip Oreopoulos find evidence using regression discontinuity methods that being placed on academic probation increases the probability that a student voluntarily leaves the university. Figure I below shows the estimated discontinuity in probation status at the end of the first year, and Figure 2 shows the impact of being placed on academic probation on the decision of male students to permanently leave the university at the end of their first year. Figure 1 Figure 2 Men 0.2 Probation status Left university voluntarily 50.1 -1.50 Fire your GPA minus probation cutoff -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 First year GPA minus probation cutoff 1) Why doesn't the mean difference between the rates of voluntary leaving for students placed on probation and those not placed on probation provide an unbiased estimate of the effect of being placed on probation? (3 points) 2) Based on Figure 1, which type of RD do you think this study is using, sharp or fuzzy RD? Explain the difference between the two. (2 points) 3) Briefly explain why the regression discontinuity estimates provide an unbiased estimate of the effect of being placed on probation? (3 points) 4) In this study, GPA is used as a running variable. Describe the role of the running variable in a sharp regression discontinuity design. (2 points)In the US, individuals can legally drink once they turn 21. We would like to estimate the effect of minimum drinking age laws on mortality using the given date 115 110 105 100 101.34 Death rate from all causes (per 100,000) 95 93.68 90 85 80 19 20 21 22 23 Age Calculate the regression discontinuity (RD) estimate based on the given figure and explain what this RD estimate means.A B C D E 1 Research Method | Characteristic 1 Characteristic 2 Strength Limitation 2 Lab Experiment Quasi Experiment Field Experiment 5 Natural Experiment 6 Correlational Study 7 Longitudinal Study 8 Observation 9 Case Study 10 Interview