Now examine the effect of training level on annual salary, with and without adjusting for age and experience.
a. Find the average annual salary for each of the three training levels and compare them.
b. Find the multiple regression equation to predict annual salary from age, experience, and training level, using indicator variables for training level. Omit the indicator variable for level A as the baseline.
c. Examine and interpret the regression coefficient for each indicator variable for training level.
d. Does training level appear to have a significant impact on annual salary after adjustment for age and experience?
e. Compare and discuss the average salary differential between training levels A and C, both with and without adjusting for age and experience.