3d. In Chicago, whether or not a student is retained is based on whether the student's standardized test scores meet a certain cutoff. A researcher decides to use this cutoff to determine the causal effect of being retained. Name what empirical strategy is being used here, and explain the reasoning behind how this strategy works. In both of the graphs below, the "index score" represents the standardized test score, which is re- centered so that 0 represents the pass-fail cutoff. PP amen 99 re Probability of grade retention 0 P _. E 0.05 E g n 5005 8 g o.1 -0.15 2 1 .5 1 o.5 o 0.5 1 1.5 2 Index score B. Relationsz between index and dropout residual 3e. Interpret the findings in Panel A of the graph. Why do you think that the probability of being retained is never 100%, even with failing test scores? 3f. Panel B shows the "dropout residual" on the y-axis. Without being too technical, think of this as a representation of the probability of dropping out. Given the findings in Panel A and the empirical strategy that is being used, what does this graph suggest about the causal effect of being retained in 6th grade