"During the design process ... [graphics editor Kevin Quealy] said he had to strike a balance between the interactive being too simple (and boring) and being too complex (and game-like, for something that’s a serious topic). ... To facilitate the sharing of a user’s results, a variable called “choices” is appended to the URL. This variable tells the Javascript which tax cuts and spending increases to display. A user then has the option to post the results to Twitter, by interacting with the service’s Tweet Button, which Quealy noted is partially why the interactive is so popular on Twitter."