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st: RE: -catplot- available for download from SSC


From   "David LB Schwappach" <dlb@h-ero.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: -catplot- available for download from SSC
Date   Fri, 21 Feb 2003 14:06:36 +0100

Greatly appreciated - thank you Nick!

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu 
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
> Sent: Friday, February 21, 2003 1:57 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: -catplot- available for download from SSC 
> 
> 
> Thanks to Kit Baum, a new package -catplot- 
> has been posted on SSC. This is for plots 
> of categorical data in Stata 8, specifically 
> for bar or dot charts of the same showing 
> frequencies, or fractions, or percents. 
> 
> (For Stata 7 or earlier there are other 
> user-written programs available in the same
> territory, such as -fbar-, -tabhbar-, -vbar-.) 
> 
> Those who have looked at Stata 8's new 
> graphics may well ask: Surely all that is very 
> well done in Stata 8, with -graph bar-, -graph 
> hbar- and -graph dot- offering a great range of 
> possibilities? 
> 
> The answer is "Yes indeed", and that is 
> what I am building on, the aim being to add 
> a convenience command in one particular 
> area. 
> 
> I work a lot with students and others who want bar 
> charts of categorical data, for example, of counts 
> of categories from one-way, two-way or even three-way 
> tables from questionnaires and other survey data. 
> In addition, many of these users want to tell me 
> for some reason that it's very easy in Excel, so 
> I really want to be able to say to them that it's 
> also very easy in Stata. 
> 
> How does Stata size up on this task? 
> 
> 1. -histogram- is optimised for histograms, 
> naturally. It can be used for this purpose by 
> invoking options like 
> 
> , discrete xla(, valuelabel ang(45)) gap(50) 
> 
> for a one-way table or 
> 
> , discrete xla(, valuelabel ang(45)) gap(50) 
> by(myvar, rows(1)) 
> 
> for a two-way table. Typing this -- or issuing 
> the equivalent through a dialog -- is a 
> little more complicated than some Stata beginners
> might expect for this task. In any case, 
> some problems then frequently arise: 
> 
> a. it doesn't take much for value labels to become 
> unreadable or to require what I call giraffe graphics, 
> in which the graphic necessitates a great deal of neck 
> movement. (That's why I have "ang(45)" in the examples 
> above.)  
> 
> b. The number of cells you can show easily and effectively 
> appears to be ~20, given that you will want value 
> labels shown to indicate the categories. Any long 
> value labels make this problem worse. 
> 
> c. Representing a 3-way table seems impossible, except by 
> producing and then combining separate histograms. 
> 
> 2. -graph hbar- etc. is good _if_ the 
> frequencies come predefined as a variable, because
> then you can just sum the frequencies. But 
> if you want Stata to do the counting for you, 
> this seems to require you to set up something 
> to count. In particular, 
> 
> . graph hbar (count) rep78 
> 
> doesn't give you the frequencies of the 
> categories of -rep78-. Roughly, we want -graph- 
> here to -contract-, not -collapse-. 
> 
> The way to do it is to calculate something in 
> advance, as in 
> 
> . gen freq = 1 
> . graph hbar (count) freq, over(rep78) 
> 
> but arguably we shouldn't have to do that. 
> And as for percents, catching missings, 
> and working with -if- and -in-: it 
> really needs a program. 
> 
> So that's the rationale for -catplot-. What it 
> actually does can be seen by reading the help
> 
> . ssc type catplot.hlp 
> 
> and then if interested you can install 
> 
> . ssc inst catplot 
>  
> Nick 
> n.j.cox@durham.ac.uk 
> 
> P.S. choosing good names is not always 
> easy. Perhaps this one is down partly 
> to the fact that I like cats. 
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