Re: st: graph combine of tabplot graphs: uncomparable bar heights

[Nick Cox <njcoxstata@gmail.com>]

-tabplot- is from SSC. You are asked to explain where user-written
programs you use come from.  Otherwise you waste the time of anyone
who thinks "That sounds interesting" but then can't find -tabplot- on
their system because it has not been installed. The small point of
giving credit to whoever wrote it I leave on one side. This is all
explained in the FAQ you were asked to read before posting.

The underlying problem is that -tabplot- internally uses a scale that
is only indirectly unrelated to the numbers being shown. In a case
like

sysuse auto
tabplot foreign rep78 , showval

the highest bar is drawn between y = 2 and y = 2.8. If the highest bar
had been on the bottom row it would have been drawn between y = 1 and
y = 1.8. This is regardless of what the highest bar represents. -graph
combine- can only align x and y coordinates; it won't restructure the
graphs internally. Similarly -yscale()- can have no effect here,
because scaling has already taken place. In fact it could not be
otherwise.

Much of the effort of -tabplot- goes into using the space available as
effectively as possible. The default is to leave 20% vertical space
between the height of the tallest bar and the line above (or
correspondingly if the bars are aligned horizontally).

You have I think two choices. One is to choose a -height()- option
separately for each graph so that the values come out as you want when
you combine them.

The second is to restructure your data, so that you use a -by()-
option as well with -tabplot-. Then the bars in each panel will be
drawn on the same scale.

Nick
njcoxstata@gmail.com


On 28 June 2013 11:34, Brunelli Cinzia
<Cinzia.Brunelli@istitutotumori.mi.it>  [edited]

>  I'm going to combine together in a single figure 3 graphs previously obtained with -tabplot- to show patients and physician agreement on the assessment of three different variables.
>
> The syntax is the following
>
> tabplot ecs_cp_q2 alberta_q0_imput, showval  percent xtitle("   " "   ") subtitle ("")  ///
> ytitle("PHYSICIAN ASSESSMENT") title("INCIDENT PAIN", size(msmall)) saving(IP_AGREE, replace)
> tabplot ecscp_neu pain_dtct_cat2, showval percent xtitle("   " "PATIENT ASSESSMENT") subtitle ("") ///
> ytitle("") saving(NP_AGREE, replace) title("NEUROPATHIC PAIN ", size(msmall)) yscale(range(0 1))
> tabplot ecs_cp_q3 any_dep_PHQ, showval  percent xtitle("   " "   ") subtitle ("") ///
> ytitle("") saving(PD_AGREE, replace) title("PSYCHOLOGICAL DISTRESS", size(msmall))
>
> graph combine  IP_AGREE.gph  NP_AGREE.gph PD_AGREE.gph,  col(3) ycommon xcommon
>
> The commands work and the figure is nice but... proportions between bar heights are correct within each graph but not between graphs: i.e the fourth bar in the first graph, which represents 35% of the sample, is as tall as the first one in the second graph, which should represent 66% of the sample. I guess this has to do with different graphical formatting rules within each graph.
>
> Is there a way to overcome this misrepresentation? I tried to use something like yscale(range(0 100)) in order to standardize yaxis scale, but it doesn't work. I find -tabplot- very useful for my proposal and it would be a pity not to be able to use it and present a "boring" table.

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