Here’s a dual line chart showing trends in life expectancy for males and females in the UK from 1948 to 2016….
The above chart is only one way of visualizing this data, starting at zero. It gives the impression of a steadily increasing life expectancy for both sexes, with little difference between them.
Visualizing starting at age 64
However, if you cut off the bottom 60 odd years, you get the impression of a much faster increase in life expectancy and you also get the impression of a more rapidly closing gap between male and female life expectancy:
Same data, two different impressions…. the first ‘calm and steady’, the second ‘rapid and intense’ – it just goes to show how easy it is to ‘distort’ even ‘hard’ data in the visualisation/ representation phase!