Post

Rich Morris
@sometimesdata.bsky.social

Lord save me! Where do people get the idea the y-axis must always include zero, and every panel in a collection of panels must have the same y-axis scale? These a fine “rules of thumb” but they are not stone commandments handed down by the #dataviz gods!!! #rstats

0 reposts28 likes

Dan Chaltiel
@danchaltiel.bsky.social

To me, a y-axis without a 0 gives a vision with an overestimated variance. If it starts at 50, you can have the impression that 52 is twice as big as 51. I find that cases where this is not problematic are rather rare. I think this is a very common technique to manipulate opinions with graphics.

Rich Morris
@sometimesdata.bsky.social

I’m happy to hear that argument. The use case I’m arguing for is to examine whether a series of trends are changing together. Each trend is incomparable on scale (eg some have a true zero, some don’t) but it is still valuable to understand if their changepoints coincide.