The following variables are in the regression below:

* earnings - yearly wages
* age
* educ - years of education
* woman - dummy
* married - dummy
* manager - dummy

**What is the need/usefulness to have age squared in the regression?**

[![enter image description here](https://i.stack.imgur.com/j8A5s.png)](https://i.stack.imgur.com/j8A5s.png)

I did another regression after this one, but I used ln(earn) instead of earn. All other variables remained the same. I would expect the R squared to be the same for both as the variables are the same but **the R squared is higher for the second regression and I'm struggling to understand why?**

[![enter image description here](https://i.stack.imgur.com/DSbOD.png)](https://i.stack.imgur.com/DSbOD.png)