arrows on whiskers of box plots

Question

I plotted box plots for a dataset of >20 million rows. The whiskers came out with little arrows pointing towards the boxes:

What do they mean?

It would be helpful if you could mention the specific software this came from. Best to also add the relevant tag. — Stephan Kolassa, Jun 02 '20 at 14:45
The major messages here to me are that you may be better off on a transformed scale and that you have enough data points to look more closely at the distribution using e.g. a kernel density estimate. — Nick Cox, Jun 02 '20 at 15:10
Those aren't arrows. They are horizontal lines (showing the fences) superimposed on individual point symbols (diamonds). — whuber, Jun 02 '20 at 16:45

score 3 · Answer 1 · answered Jun 02 '20 at 14:56

3

It means nothing. It is a visual artefact of many black wheels overlayed on top black lines.

answered Jun 02 '20 at 14:56

Tim

I am also thinking of a visual artifact where whiskers combine with points. But why would the points be more like diamond shape than round shape? – Sextus Empiricus Jun 02 '20 at 18:08
@SextusEmpiricus because of low resolution. – Tim Jun 02 '20 at 18:13
I see now, the whiskers are not only a horizontal a stripe but also a vertical stripe. So the vertical stripe makes the circle a pointy shape. – Sextus Empiricus Jun 02 '20 at 20:26

1 Answers1