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When graphs have no scale

Plenty of more intelligent folks than I have blogged about this topic many times (Forbes, Contrast, etc.) but it doesn’t make the topic of misleading data visualisation any less relevant. Putting aside Fox News, Microsoft and every local newspaper you ever have lain your eyes upon for a moment, 7-eleven.com (an American convenience store/corner shop type affair) have an election related subsite called “7-election” where they’re running some form of poll based on the in-store actions of their customers to gauge support for the two main candidates in the 2012 Presidential Election.The mini-site doesn’t explain how they’re determining results but the red and blue cups might be a clue.

The problem: they have a massive colourful graph on the homepage of the site, intending to reflect support nationally and on a state-by-state basis. The graphs do not have an axis or a scale, nor do they have a 0-mark of any form.

Which makes them wrong.

Nice image. The candidates look close. Except they’re 16% apart. 16% represented by 45 pixels. Fine, except that means the graph should have a zero point marked, here:

So really what we’re seeing is this:

I don’t know much about the political affiliation of 7-eleven corporately, but it seems to me there’s no great benefit in making this so misleading.

Which means that if the graph was accurate and the 0-point was the edge of the blue cup (as your eye would make you believe) then this would be a truer representation:

I’m glad I’m not a designer.