Re: jitter documentation

[Ethan A M. <me...@uw...>]

On Thursday, 15 October 2020 08:02:27 PDT Allin Cottrell wrote:
> Maybe I'm missing something, but isn't the documentation for 
> "jitter" backwards with respect to the swarm/square choice?
> 
> The text reads thus: "The default jittering operation displaces 
> points only along x. This produces a distinctive pattern sometimes 
> called a "bee swarm plot". The optional keyword square adjusts the y 
> coordinate of displaced points in addition to their x coordinate so 
> that the points lie in distinct layers..."

The text is correct as written.  Perhaps the attached figure,
combining two plots from jitter.dem, will clarify.

Left panel:
	original data, randomly distributed on y, all x values the same
Center panel:
	"beeswarm" result from displacing points along x
	if they would otherwise overlap.
	Points are still randomly distributed on y.
Right panel:
	"square" plot uses the x displacements that would
	generate a beeswarm plot, and adds an y displacement
	that is effectively a floor(y) operation where the unit of
	the floor operation is the "overlap" parameter to jitter.

> 
> In the demo and in my own usage it seems the default is in fact to 
> displace in both the x and y dimensions while "square" limits the 
> scatter to the x dimension. (Except that in some cases I'm not 
> getting any y displacement with either choice, but that's another 
> issue.)

(figure attached)

	Ethan