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st: Re: graph question

From   "Martin Weiss" <>
To   <>
Subject   st: Re: graph question
Date   Sun, 19 Apr 2009 19:35:36 +0200


With CIs :-)


//create data
set obs 600

gen arm= cond(_n<301,0,1)
lab def arms 0 "control" 1 "experimental"
la val arm arms

egen float interval = fill(0 1 3 6 9 12 0 1 3 6 9 12)
egen float measurement = seq(), from(1) to(50) block(6)

//fictional value of measurement (no systematic diff btw control and experimental group)
gen mymeasurement=rnormal()

mean mymeasurement, over(arm interval)

collapse (mean) mean=mymeasurement (semean) semean=mymeasurement, by(arm interval)
gen lb= mean-invnormal(0.975)*semean
gen ub= mean+invnormal(0.975)*semean

twoway (rcap lb ub interval, sort) (scatter mean interval), ///
xlabel(0 1 3 6 9 12) by(, legend(off)) by(arm, note(""))

----- Original Message ----- From: "Nikolaos Pandis" <>
To: <>
Cc: <>
Sent: Sunday, April 19, 2009 6:19 PM
Subject: st: graph question

Hi to all.

I would like to ask the following:

I have continuous data for two trial arms (control and experiment).
There are 50 measurements per arm.
Data is collected at 6 time intervals.

I would like to plot a bar chart with the x axis showing the intervals (0, 1, 3, 6, 9, 12 months). Within each interval I would like to have one bar for the control and one for the experimental group.
The y axis shows the mean of the measurement of interest.

Additionally, I would like to show the confidence intervals at each interval per treatment group.

Alternatively, I would like to draw a line plot with the same y and x axis information, except that the two lines would represent the control and the experimental groups.

Thank you very much,


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