How Charts Work: Understand and explain data with confidence

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Charts of deviation

Emphasise variations above or below a fixed reference point. Typically, the reference point is zero, but it can also be a target or a long-term average. These types of charts are also often used to show sentiment (positive/neutral/negative).

In 2014, UNESCO asked me to review graphics published in a series of reports on access to education in the Asia-Pacific region. I spent a pleasant week in Bangkok working with a knowledgeable and talented team whose passion for their work was unquestionable. We spent most of our time discussing why the charts in their reports were uniformly awful.

For example, take the figure below, ...