is on the same unit scale as the outcome variable we are predicting. 

Remember that under the hood, [`lm`](https://www.rdocumentation.org/packages/stats/versions/3.5.2/topics/lm) is one-hot encoding factors to indicators, but [`model.matrix`](https://www.rdocumentation.org/packages/stats/versions/3.5.2/topics/model.matrix) can be used to do so manually.  

Also be sure to [check out this blog post](http://blog.yhat.com/posts/r-lm-summary.html) on how to fit and interpret linear models. 

### See Challenge 