Thanks a lot, I will try this and see how it works!
-----Opprinnelig melding-----
Fra: [email protected] [mailto:[email protected]] På vegne av Maarten buis
Sendt: 17. november 2008 11:45
Til: [email protected]
Emne: Re: st: from normal to bimodal distribution
--- Linn Renée Naper <[email protected]> wrote:
> How do I tell Stata to draw random variables or generate a stochastic
> variable with a bimodal distribution? Can the rnd-command by Hilde be
> used?
You can create a mixture of Gaussian (normal) distributions, like in
the example below: the local p represents the probability of belonging
to group 1, the locals mu1 and mu2 represents the means of group 1 and
2 respectively, and the locals sd1 and sd2 the standard deviations in
group 1 and group 2.
*--------------- begin example -----------------
drop _all
set obs 10000
local p = .5
local sd1 = .75
local sd2 = 1.5
local mu1 = -2
local mu2 = 2
gen u = uniform()
gen e = invnorm(uniform()) * ///
cond(u < `p', `sd1', `sd2') + ///
cond(u < `p', `mu1', `mu2')
hist e
*---------------- end example ---------------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
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 N515
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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