On: NFL players: height and weight over time

[sesqu]

One could argue that the large difference in sample sizes (more than fivefold) justifies scale manipulation to bring the variances into line, but it doesn't appear to me that the author normalized on variance at all (the axis should be something like 800-2000).

[ronaldx → sesqu]

I agree with what you say.

To correctly compare the variances, the scale should be adjusted according to the square root of the ratio of sample sizes.

The author has not done this correctly, but I claim that zeroing the axis would be further from the correct graph.

[craigmbooth → ronaldx]

Ah, you are correct, thank you. Apparently I wasn't thinking clearly when I normalized the axes to have the same absolute ranges.

[sesqu → ronaldx]

I generally feel that zeroing the axis is never wrong, but yes, in this instance a (properly) cut axis would be better than correct. However, it should be apparent at a glance, and the presence of the other two graphs complicates things as well, so I have some reservations.