# st: Sampling scheme

 From tiago.pereira@incor.usp.br To statalist@hsphsun2.harvard.edu Subject st: Sampling scheme Date Thu, 12 Jul 2007 20:00:51 -0300 (BRT)

```Dear statalisters,

I have a variable in which observations take one out of 9 values:
11,12,13,21,22,23,24,31,32,33

So, observations assume the values 1`i', 1`i', 3`i', for i = 1,2 or 3.

Assuming that I have 1000 observations , I would like to:

(1) randomly sample, say, 25 observations satisfying the condition ==1`i'

(2) randomly sample 50 observations satisfying the condition ==2`i'

(3) randomly samply another 25 observations satisfying the condition ==3`i'

Then, I would like to count the frequency of each `i' in the first, second
and last samplings.

For example, considering yet the example above, assume that among the
first sampling (25 obs), 12 observations were 1`3', 10 were 1`1' and 3
were 1`2' (12+10+3 = 25 sampled observations).

I would like to obtain the following result:

`1' = 10
`2' = 03
`3' = 12

Is it possible to perfom such sampling scheme using Stata?

Thank you very much.

Tiago

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