Now, let's look at a different linear combination. Suppose we are interested n comparing the average mean log income for no college education (< 12; 12) to the average mean log income for any college education (13 15; 16;> 16).

1. Write out the linear combination of means we are after in terms of s. Be sure to include all groups to explicitly show work.

2. What are the coefficients of the linear combination in (1)? (i.e. What are the C's)

3. Write out the estimator of the linear combination (g)

4. Obtain an estimate using the group averages directly.

5. Calculate the SE of the estimate using the Display 6.4. 6. Construct a 94% confidence interval for the linear combination.