(b) (2 points) Suppose you are interested in conducting a study where you compare the average MATH 3B grades (Yi) of students enrolling in a special math tutoring pro- gram (treatment) versus those without the tutoring (control). However, you want to ensure that your study's design eliminates selection bias. How can you eliminate this issue when sorting your student participants within the context of this experiment? What can you do to maximize the e?ectiveness of your solution? Please make sure your response is speci?c and concise. Page 3

2. Selection Bias. Let Y, be some outcome variable for an individual i and D, be a binary variable that takes on a value of "1" if the individual receives some treatment. Recall the following potential outcomes framework: (0) , if D, = 0 Y = (1) , if D, = 1 where yi(1) is the observed outcome for those that receive the treatment while y.(0) is the outcome for those that did not receive it. Thus, Y, = Digi(1) + (1 - D.)y (0). In this framework, we estimate E(Y,| D, = 1) - E(Y|D, = 0)