Re: Jittering interval and ordinal variables in graphs. was "What does this graph means?"

Posted by Andy W on Jan 30, 2013; 9:28pm
URL: http://spssx-discussion.165.s1.nabble.com/What-does-this-graph-means-tp5717745p5717839.html

Ahh! I made a mistake in my error bar intervals - I assume the t-critical value was 1.96, but it is not with so few cases, it is actually 2.201 (as Bruce's post shows earlier), and so my example you should go out [2.201*sqrt(1 + 1/12) = 2.29] standard deviations. Still the logic is the same, you could just figure out the multiplicative factor yourself and then use that in the legacy dialogs or the GGRAPH chart builder.

Re: the confidence ellipse R plug-in, yes I have used it and it is nice, I would like a native SPSS application though, with data you can plot in an actual SPSS plot (I'm not asking you to do this Jon, it is simply on my long academic bucket list that who knows I will have time to do!)

A very cool recent article demonstrating the utility of confidence ellipses (especially for mixed models) can be found here (Friendly et al., 2013).

I've dug into the source for the ellipse function in R, and I will tell you what that is a sight of complexity to behold. Here are few simpler examples I think I can wrap my head around though to mimic in SPSS, http://stats.stackexchange.com/a/9900/1036. This seems to me doable with the current constraints (submit data to a matrix procedure, get out a series of x,y points to draw in GGRAPH).

Contour plots though would be much more difficult given the current constraints to GGRAPH as far as I can tell.