Suppose we are interested on the intergenerational transmission of educational attainment. To that end, data on n = 722 employed men is used to estimate the following regression: educi = 10.36 0.094sibs; +0.131meduc; +0.210feduc + where educ denotes the man's total years of education, sibs his number of siblings, meduc his mother's total years of education and feduc his father's total years of education. (a) Discuss the estimated coefficient on sibs. Does this have the sign you would expect? Holding meduc and feduc constant, by how much does sibs have to increase to reduce predicted years of education by one year? (b) Give the descriptive interpretation for the estimated coefficient on meduc. Do you think this provides a reliable estimate for how a mother's educational attainment influences that of her son? (c) Man A has no siblings, and his mother and father each have 12 years of education. Man B has no siblings, and his mother and father each have 16 years of education. What is the predicted difference in years of education between B and A? (d) Other than sibs, meduc, and feduc, what other factors might affect educ? Are any of these likely to be correlated with sibs, meduc, or feduc?