st: drop 'em OR it depends

[Tim <lists@timbp.com>]

New semester starts in about a week.
One thing I had difficulty with last semester was getting the data 
provided into the form needed for the analysis. I could get reshape to 
work, but had to look it up every time, and it still took several 
attempts every time.
So I've been looking again at Hills and De Stavola, "A short 
introduction to Stata for biostatistics", chapter 9. (files at net from 
http://ww.stata.com.data/hs/; net get book)
In section 9.5 they cover reshape.
In section 9.6 they cover _N and _n.
The examples in section 9.6 use the fevlong dataset. When I tried using 
fevwide reshaped to long, I did not get the results in the book. Only 
after dropping missing observations did it work.

So my question is, should dropping missing obs be normal practice after 
reshaping from wide to long, or does it depend on what I want to do with 
the long dataset?
And if I dont' drop 'em always, when do I keep them?

Tim
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