Working Branch into Development Merge

This branch contains the code related to the addition of the price tercile variable. This merge request will complete this project.

My one concern is about the data dictionary. I am concerned the merge request will over-write other changes made to this file.

I have saved a copy of the data_dictionary being merged (that contains additional models using price tercile as an interaction term with other variables), so please let me know if you need that to incorporate those changes into the development branch.