As both the controls and the cases are random draws from a normal distribution and the two are uncorrelated you can just draw 1000 random numbers from a normal distribution and call the first 500 controls and the last 500 cases.
set obs 1000
gen control_case = invnorm(uniform())
gen status = _n >500
Hope this helps,
Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Natarajan, Raj
Sent: vrijdag 13 juli 2007 16:47
To: [email protected]
Subject: st: RE: selecting random samples and run a simulation
I sent this e-mail yesterday but did not get any response. So I am resending hoiping it will come out.
________________________________
From: Natarajan, Raj
Sent: Thu 7/12/2007 8:26 AM
To: [email protected]
Subject: selecting random samples and run a simulation
I would like to draw a random sample of 500 controls and 500 cases and calculate the odds ratio; repeat the process for 1000 times.
Example: (draw random sample)
matrix means=(0, 1.4)
matrix stdev = (1, 1)
draw norm control case, n(500) m (means) sds(stdev)
the outcome for the first 5 observations will look like this:
control case
-1.315189 .1754738
-.6195259 -.4363556
-1.18018 .2124426
-.2960889 -.5825416
.4534519 -.1245893
PROBLEM: I would like the outcomes for controls and cases to be in one column and create a new variable called "status" which is 0 for control and 1 for case.
Control_case status
-1.315189 0
-.6195259 0
-1.18018 0
-.2960889 0
.4534519 0
.1754738 1
-.4363556 1
.2124426 1
-.5825416 1
-.1245893 1
I have to run the logistic regression to calculate the odds ratios; and repeat the process with different variances.
I would like to know how to make the outcomes arranged in one column with the creation of the variables "control_case" and "status".
Thank you for any suggestion.
Raj
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