how do I create a subset that is not a SRS but follows a given distn (specify the mean and SD)

Question

I have a large dataset and I need to subsample to form two groups. One is an SRS (that is easy). The other is a purposeful sample that will match a given distribution. I have the data for the distn I am trying to match, and know the mean and SD. How can I do this?

squesen407 · Answer

A is approx bimodal; this is the group I want to match. B is a much larger (10x larger) population, strong left skew  The mean of A << the mean of B. Trying to get a subset of B to match A.

Get a freq table for group A.

Get a histogram of group B, match the bin size to group A.

Take a SRS from the first bin in group B of size n that matches group A, to get the same n in the sample of B as in A.

Repeat for each bin across the histogram in order to build the complete subset of B.

Used a two-sample t to make sure the means weren't too different between groups.

This took a while to build and I had to be careful not to accidentally select the wrong rows. But it worked.

Jeff_Perkinson · Answer

I'm glad to hear it Sarah.

Can you share what method you ended up with?

-Jeff

squesen407 · Answer

I think I figured it out.

Thank you!