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st: sampling problem


From   "John allfish" <[email protected]>
To   [email protected]
Subject   st: sampling problem
Date   Tue, 19 Jun 2007 14:50:34 +0000

I have been trying a number of ways of sampling. I want to use the samplepps command which has the following syntax:

samplepps newvar, withrepl size(varname) ncases(integer)

What I want to do is to create a program which will run this command several times. The problem is that I want the ncases(integer) to be different. I have a vector of values which I want ncases to take on. So I run I may have 5 different values in my vector. I want to run samplepps five times with ncases taking on the value of the first row of the vector for the first time, the second row the second time and so on.

Is there any quick way of doing this or do I just have to manually enter the number each time?

Thank you,
John




I want to sample data on the basis of counterfactuals - so what would the distribution of income in 2007 look like if individuals had the distribution of health of 1985.

So imagine I have the following data

id income2007 health2007 health1985 wgt1985
1 10 1 1 65.38
2 10 1 1 153.91
3 20 1 1 458.34
4 20 1 1 484.2
5 40 2 1 906.1
6 40 2 4 943.96
7 60 4 5 1176.87
8 60 4 5 1389.91
9 100 5 5 1716.93
10 100 5 5 4067.68

where weight is the sampling weights for the 1985 data (I also have sampling weights for the 2007 data). The order of the 1985 data makes no difference to the 2007 data it is just pasted in to obtain the health distribution.
What I want to do is sample from the 2007 data to make the distribution of health in 2007 look like that in 1985. So I want to draw individuals from 2007 according to the distribution of health in 1985 so I draw individuals with health=1 with prob=0.4, health=2 with prob=0, health=4 with prob=0.1 and health=5 with prob=5 (where the probabilities comes from the health1985 distribution). This should give me a hypothetical distribution of income in 2007 if the distribution of health was as in 1985.
I cannot see how to do this with the bsample command. Further I am not sure then how to incorporate the sampling weights to ensure that my samples correctly represent the population distributions.
Any help would be much appreciated.
Yours,
John

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