Dos and Don’ts of Data Visualisation
Whether on purpose or not, a statistician can mislead an audience with a chart. This article explains some chart design principles and common mistakes novice data analysts make. Think about the statistical charts you have seen on billboards, in the news, and in research studies. Using these principles as a guide, would you classify any of those charts as misleading? Be sure to take note of the suggestions for successful dashboards.
Make charts easy to read
Do use direct labelling wherever possible, avoiding indirect look-up
If possible, label lines individually and avoid legends.
You want to allow instant identification of the lines but looking them up in a legend takes way too much time. Often the legend is below the chart and its elements are in arbitrary order. Instead, place the labels close to the lines.
However, placing a label next to a line could become an issue when multiple lines end at the same point. In that case, place a legend below the chart.