st: dividing a data set into estimation and validation sets

["Richard Hiscock" <rhiscock@netspace.net.au>]

I would be grateful for some direction to the area in the stata manual 
that explains how to do the following
I am trying to split a dataset (n ~1500) into an estimation sample and a 
validation sample  by random sampling (n = 400-500) from the dataset

Later I wish to compare results with that using bstrap techniques
Thanks in advance
Richard Hiscock 

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