Ask HN: Please review my most recent side project (cost behavior analysis)

I made this web app because I found doing cost behavior analysis for my managerial accounting homework very tedious and relatively time-consuming.<p>Cost behavior analysis is the process of dividing a mixed cost into its variable and fixed components (math: Finding the slope and y-intercept of a line or "m" and "b" in the equation y = mx + b)<p>This app is written in Python on the Tornado framework and makes use of numpy, matplotlib, and MongoDB.<p>What can I do to make this app easier to use and more useful?<p>The app: http://apps.charleshooper.net/cost-behavior-analysis/<p>Sample analysis of my power bills: http://apps.charleshooper.net/cost-behavior-analysis/results/4cd58f4399fda52f44000000/