On May 20, 2011, at 7:12 PM, Joseph Boyer wrote:
Is there a package in R that can do a variability plot?
A variability plot is a kind of categorized dot plot. (If there is a
lot of data in each category, box plots are used rather than dot
plots.)
Usually, the categories are factor level combinations. All the dot
plots appear in the same window; below the x-axis a hierarchy of
factors
shows which dot plot corresponds to which factor-level combination.
Examples can be seen
http://statsoft.com/support/blog/entryid/64/user-defined-variability-plots/
and
http://www.public.iastate.edu/~wrstephe/stat495/GaugeRR_WaferThickness_JMPOutput.pdf
I'm afraid I developed an allergic response to SixSigma DMAIC bul....t
after being dragged through a GreenBelt indoctrination session. The
"teachers" did not want to hear about either regression or
nonparametric statistical approaches because it wasn't in their
approved curriculum. I'm sure you can whip up something quite like
that with R. In fact it would be good teaching exercise. Go for it!
You could alternatively read the Posting Guide about what is requested
of a poster on R-help.
By reordering the factor names in the function call, the user can
reorder the factor level combinations on the graph, making it easier
to do the visual comparisons of interest. The user should also have
the option to draw line segments at factor level combination means/
medians, and to connect the category means/medians to make visual
comparison easier.
The only softwares which I am aware of which produce such a plot are
Statistica and JMP. I have found these plots to be more powerful than
lattice-style categorizations in their ability to allow the user to
conveniently process experimental data visually.
David Winsemius, MD
West Hartford, CT
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