Name

Description/Function

Stata Command

Frequency
Table Plot

Created
by the prolific Nicholas Cox (Durham
University, UK),
this command “plots a table of frequencies, fractions or percents in
graphical form” (Stata help file). Well
over a dozen options exist to sex up the plots. A handy graphic to visually assess
concordance between two categorical variables.

tabplot

(Cumulative)
Distribution Plot

Also
authored by Nick Cox, these plots chart the cumulative distribution of one or
more variables. Although the two plots
are subtly different, they essentially produce plots of cumulative
distributions as the proportion or frequency ≤ to each value. The first command, distplot, appears to be a succession of
the latter command, ordplot, although –ordplot explicitly specifies that the
variable be ordinal.

distplot,
ordplot

Paired
Observation Plot

Again,
credit goes to Nick Cox. This plot is
ideally suited for paired data sharing a time component (e.g.
before/after). The barebones command
requires two yvariables where the difference or ratio between the two is
plotted on the yaxis and the observation number on the xaxis. Helpful for visualizing change between two
finite points by subject.

pairplot

Twodimensional
Biplot

This
official Stata command plots the relationship between observations and
variables. The graph returned plots
the observations as points and the relative position of the variables as
arrows. This command seems helpful in
visualizing where observations and variables cluster as well as correlation
between the variables.

biplot

BlandAltman
Plot

First published
by Bland and Altman in 1983, this graph assesses measure of agreement between
two variables. The authors used
continuous variables in their paper but note that categorical variables can
also be analyzed. The plot is intended
as a replacement to using the correlation coefficient to assess
agreement. The graph plots the
difference of two (paired) variables versus their average and state that with
this plot “it is much easier to assess the magnitude of disagreement (both
error and bias), spot outliers, and see whether there is any trend” (Altman
& Bland, 1983). Another Brit, Paul Seed, wrote the Stata programs for these plots.

baplot,
bamat,
bagroup

Although I'm no longer planning to use any of these concordance plots or tests for my dissertation, I figured I'd post them anyway since I went to the trouble of jotting them down on my whiteboard. (I also need the whiteboard space and wanted to move the information online before unceremoniously erasing my table.)
This isn't intended to be an exhaustive list of all the tests and techniques for assessing concordance but I think I managed to get a fair number of them. If nothing else, this can be used as a good jumping off point for further research.
This isn't intended to be an exhaustive list of all the tests and techniques for assessing concordance but I think I managed to get a fair number of them. If nothing else, this can be used as a good jumping off point for further research.
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