[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
Re: st: RE: prtest and fweights
At 12:53 22/09/2004, Ronan M Conroy wrote:
A possible way around this problem is to use -expgen-, downloadable from
SSC. -expgen- is an extended version of -expand-, and does not retain
observations with a zero or missing value for the expression, unless the
user specifies the -zero- or -missing- options. -expgen- can also generate
new variables, containing the sequence number of the duplicate observation
(amongst its duplicates in the new data set) and the position of its parent
observation in the old data set.
Nick Cox wrote:
I can't comment on why not. I guess no one asked, or no one thought of
doing it.But beware of -expand-. If an observation represents a zero frequency, it
will be retained. You will see a warning but it's a behaviour that you
might not have anticipated.
For the moment,
I transcribe tables from papers that I am reviewing into Stata frequently,
to cross-check stats, and it's easy to transcribe a zero without
remembering that this will create a single observation in the expanded dataset.
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
5th Floor, Capital House
42 Weston Street
London SE1 3QD
Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
or 020 7848 6605 International +44 20 7848 6605
Opinions expressed are those of the author, not the institution.
* For searches and help try: