It came up this week with this map on poverty and deprivation in London, part of our London: the data series. Recently we've been using the colour scale on the map below, which is a variation on the famous traffic light collection of colours - for the Guardian, this tends to go from green, meaning good, or low - up to red, meaning bad or high. It's used by map makers and newspaper designers all the time. But is it any good?
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