Part A: The research team would like to use a differences-in-differences / event study design for this evaluation, using the following model structure: gigst - > BADt. + 3. D., + on + at+ 6alligat where yiart is the standardized academic achievement outcome of student i in grade g, school s, in academic year t; a is a student fixed effect; x, are academic year fixed effects. Error terms, ; are clustered at the local school district level, to take into account of the serial and cross-sectional correlation of unobserved determinants of achievement outcomes among students. (Ignore the notation 6 t - it is a typo in the equation.) Outcome: The yo, academic achievement outcome is normalized to have mean equal to zero (0) and standard deviation equal to one (1), such that the estimated effects are interpreted as effect sizes. Treatment: Treatment indicators for each student i are defined as the following indicator variables: DK ,= 1{t - IY, = k}, the year k before or after initial assignment (IY,) of the student to a school consolidated at time t. The reference category is year k = - 1, the year before assignment to treatment. . Describe the interpretation of the coefficients Po, k = {-4, -3, -2} [5]