# Re: st: RE: Graphics with averages of variables (over other variables)

 From oezguer.guererk@uni-erfurt.de To statalist@hsphsun2.harvard.edu Subject Re: st: RE: Graphics with averages of variables (over other variables) Date Wed, 10 Jun 2009 13:15:23 +0200

```Nick, this works! Thank you very much!

Nick Cox schrieb:
```
```The code you tried is undoubtedly wrong. It is quite inconsistent with
the syntax specification. Some parts of the -graph- syntax allow data
```
reduction on the fly, but not the -twoway- command.
```There are various ways to approach this. One of the easiest is to
calculate your averages in advance. -egen mean()- in conjunction with
-by:- or a -by()- option is in turn a convenient way to do that. In your
```
case, the syntax sounds like bysort group period: egen mean = mean(myredpts)
```to be followed by a call to a graphics command. I think you should check
```
out -tsline- or -xtline-. Nick n.j.cox@durham.ac.uk
```oezguer.guererk@uni-erfurt.de

```
I would like to create "twoway connected" graphics of a variable called "myredpts" on the Y-axis and the variable "period" on the X-axis. "myredpts", however, should be averaged over several "subjects" belonging to the same "group", for each "period".
```
```
I use the command: "twoway (connected mean(myredpts) period) if treatment == 1, by(group)" which is apparently wrong because of the "mean"... If I skip mean and use only "twoway (connected myredpts period) if treatment == 1, by(group)" then stata draws in each period several points for several subjects and connects them, I, however, want Stata to draw only one single data point for each group consisting of 4 subjects in each period and connect these for the consecutive 20
```periods.

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```
```
--
Dr. Özgür Gürerk

Lehrstuhl für Mikroökonomie & Laboratorium für experimentelle Wirtschaftsforschung
(Microeconomics & Laboratory for Experimental Economics)

```
Universität Erfurt, Nordhäuser Str. 63, D-99089 Erfurt
```Tel: +49 361 7374561
Fax: +49 361 7374569
www.uni-erfurt.de/elab
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```