Of the 6,325 kindergarten students who participated in the study, almost half or 3,052 were eligible for a free lunch program. The categorical variable sesk (1 == free lunch, 2 = non-free lunch) is a coarse proxy measure of family socio-economic status. If we think that children who begin school at some socio- economic disadvantage are likely to score lower on the standardized test of reading and arithmetic skills, then we should examine the proportion eligible for free lunch by type of class in kindergarten. Is the proportion elegible for a free lunch in the regular class with full-time aide statistically different from the proportion we observe in the other two types of class? If you think that there is a statistical difference, what effect would you predict the difference will have on the observed effect of class isze on test scores? Will the difference in the proportions of students eligible for free lunch amplify or attenuate the difference from class sizes?