Andy – Great logic. I’m trying to get more people to think carefully like you’re doing here rather than just going with whatever minimum and maximum values that their software program randomly gives them.

It could be argued that for a percentage figure, the proportions of the white space are just as important, in which case the first graph is dishonest.
Fundamentally though I think it’s a question of context. If 100% is a realistic target / expectation (eg election turnout), then having anything other than a “full” axis is dishonest, while if it’s always something that will be lower values (eg election results by party) then a proportionate axis would seem entirely legitimate.
Even when 100% is still achievable, as Ann says we can control the message by changing the axis from 30% (against which 26% looks TOO good) to 50%, so that we can focus attention on the 26% without creating depression all around. It doesn’t have to be 30% or 100% – there are points in between!

Last one. From the Economist. The percentage of scientific papers with spreadsheet errors. Axis stretches from 0% to 40% (just past the biggest number), even though it’s possible that all 100% of papers could’ve had spreadsheet errors. https://twitter.com/TheEconomist/status/773713844573237249 I’m sure some people choose to use axis minimums and maximums to be dishonest, but that’s not what I’m advocating.

This example uses units (debt in trillions), not percentages, but it’s another Option A example. The axis stretches just past the biggest number. https://twitter.com/acotgreave/status/790539189863477248