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Build a linear model to estimate the relationship between the log of wage ( lwage) and education ( educ). The effect of cigarette smoking is slightly smaller when faminc is added to the regression, but the
xi fixed). But as x increases, the variance of βˆ 1 increases relative to Var(β% 1 ). The bias in β% 1 This is the chapter where I expect students to follow most, if not all, of the algebraic derivations. cx 2 + ) = c 2 + x. Therefore, ()cy cy 11 +−+i () = (c 1 + yi) – (c 1 + y) = yi – y and (c 2 + xi) –The example in the text is interested in the return to another year of education, or what the percentage change in wages one might expect for each additional year of education. To do so, one must use the \(log(\) wage \()\). This has already been computed in the data set and is defined as lwage. yi) on (c 2 + xi), and β% 1 = βˆ 1. The intercept is β% 0 = ()cy 1 + – β% 1 (cx 2 + ) = (c 1 + y) – βˆ 1 (c 2 + cx 2 + ) = xi – x. So c 1 and c 2 entirely drop out of the slope formula for the regression of (c 1 +
educated people like to get more out of life, and so, other things equal, they sleep less (β 2 < 0). Because statistical inference is no more difficult in multiple regression than in simple regression, As far as statistical properties, notice how I treat the problem of including an irrelevant variable: iv) Again, we can apply part (ii) with c 1 = 0 and replacing c 2 with log(c 2 ) and xi with log(xi). course, that this change prate is possible (if, say, prate is already at 98, this interpretation makesmy bias, but it also reflects reality. It is, of course, very important for students to understand the