Interpreting multiple regression coefficients
You fit by OLS.
Interpret precisely. Why can differ in sign from the simple regression of on alone? What changes in log specifications?
Show a hint
The phrase to make precise is "holding fixed." The Frisch–Waugh–Lovell theorem says can be obtained from a regression involving residuals.
Your answer
This one is open-ended. Work it through, then check your reasoning against the full solution.