You decide to substitute the continuous IQ variable for a se…

You decide to substitute the continuous IQ variable for a series of dummy variables indicating quartiles. IQ_1= 1 if the respondent is in the bottom quarter of the distribution, IQ_2=1 if the respondent is between the 25th and 50th percentile, IQ_3=1 if the respondent is between the 50th and 75th percentile, and IQ_4=1 if the respondent is in the top quarter of the distribution (so, the IQ_1 people are the “dumbest” and the IQ_4 people are the “smartest”, again, assuming you trust IQ tests). You re-run the regression and get the following output: Which of all the statistically significant coefficients (not just the IQ variables) has the largest association with wage? How do you know? 

Now, you decide to run the original regression, except using…

Now, you decide to run the original regression, except using the natural log of wage as the dependent variable. You get the following: Interpret the coefficient on educ (again, just say in words what the coefficients means; do not worry about practical significance).