Humans are predisposed to notice patterns (the whole) before noticing its constituent parts.

This phrase from Nicola's post on Gestalt and the role of the familiar in perception came to mind when Guido Fawkes unearthed this gem from Guardian Media Group's (GMG) annual report.

One of the most established patterns - in the Western world, at least - is to read across the page from left to right. When we display time in a figure, we adopt this convention to move chronologically across the page.

An alternative convention, most often used in tables but also some figures, is to read from top to bottom. Again, we can use this when displaying time, moving from oldest at the top to most recent at the bottom.

These conventions have been somewhat scrambled by GMG in a horizontal bar chart showing revenue since 2007:

This isn't in itself problematic. The difficulty is caused by inverting the convention for displaying a time-series, producing a curious effect: whether one reads left to right or from top to bottom we are presented with an increasing set of numbers and - strikingly - increasing bar sizes.

From our experience we know this pattern suggests an *increase* over time which, for company revenue, is 'a good thing'.  Many readers will skim read the report and be left with the impression GMG is in rude health. I humbly suggest that this is somewhat wide of the mark.

Guido's redesign using a vertical bar chart better illustrates the story of falling revenue:

Here, we are presented with another familiar pattern rather more consistent with the data: a clear, continuous *downwards* trend. Somehow, things seem a lot worse on this redesign, even though the data is the same.

Make no mistake, there are far worse crimes of data presentation: no facts have been *omitted* from the original figure: it does show that revenue fell from £593.9m in 2007 to £255.1m in 2011. Instead, the facts have been *obscured* by the mixing up of established conventions, producing a familiar pattern which misleads the casual reader.

The example shows the importance of Nicola's quote at the top of the page. When we produce a figure, we tap into our reader's pre-programmed pattern recognition before they read the detail. This affects how the data is perceived, whether we intend it to or not. In this case, we're left with the impression - however unfair - of a designer attempting to sweeten a rather bitter pill with some clever graphics.

[Thanks to Guido Fawkes for a super-fast reply to my request for the images used in this post.]

UPDATE: thanks to pynt0 in the comments for spotting that there's an error in the redesign: the '11 bar looks like it's showing 225 rather than the correct 255.