A/B Statistical Comparison for graph_page_data.php

Because of some issues with git rebase, one of this commits is poorly named, and the one that is named "A/B Statistical Comparison for graph_page_data.php" is not the complete work for this project.  Hope that is okay -- if not, please let me know.  I don't know whether it makes sense to rename or rebase changes that have been pushed to my fork of the repository.