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# Re: st: twoway bar

 From Nick Cox To statalist@hsphsun2.harvard.edu Subject Re: st: twoway bar Date Wed, 28 Mar 2012 13:49:02 +0100

```In each of your graph calls, you specify that -group- defines the x
axis variable; inevitably -twoway- does exactly what you ask for and
plots bars etc. on top of each other.

You may be expecting default behaviour like that of -graph bar-, but
-twoway bar- does not behave in the same way,

One way round this is to use an offset. The following gives an example

sysuse auto, clear
egen mean_turn = mean(turn), by(foreign)
egen mean_trunk = mean(trunk), by(foreign)
label var mean_turn "Mean of Turn circle, ft"
label var mean_trunk "Mean of Trunk space, cu. ft"
gen foreign1 = foreign - 0.1
gen foreign2 = foreign + 0.1
twoway bar mean_turn foreign1 , barw(0.18) ///
|| bar mean_trunk foreign2, barw(0.18) xtitle("`: var label foreign'")
base(0) xla(0 "Domestic" 1 "Foreign")

SJ-7-1  gr0026  . . . .  Stata tip 42: The overlay problem: Offset for clarity
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Cui
Q1/07   SJ 7(1):141--142                                 (no commands)
tip for graphing several quantities on a continuous axis

which is accessible to all at

http://www.stata-journal.com/sjpdf.html?articlenum=gr0026

Nick

On Wed, Mar 28, 2012 at 1:29 PM, ofran almossawi
<ofran.almossawi@gmail.com> wrote:

> I have done a two way bar plot but stata keeps stacking the bars and the sd
> lines on top of each other instead of laying all four columns side by side.
>
> I have compared the pain scores of two groups of patients post caesarean
> section, before and after taking their pain medications. The sm group take
> their own pain killers, and the nsm group are given the painkillers by the
> midwves.
>
> This is the code that I used:
>
> twoway (bar meanpain group) (rcap  upper_pain lower_pain group) (bar
> meanmed group) (rcap  upper_med lower_med group), by(group)
>
> i'm not sure where i'm going wrong with this.
>

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