Michael Hills' program -unique- (available from SSC) should help here.
see also -duplicates tag- and -egen..group()- (both part of official
Stata) for other possible approaches.
Phil
At 09:48 PM 25/02/2004 +0000, you wrote:
Hi,
I have a database of 40,000 clinic visits, with multiple visits by each
patient (patient_id). How do I count the number of patients seen?
Thanks
patient_id
CGHC:FP:0002
CGHC:FP:0002
CGHC:FP:0002
CGHC:FP:0002
CGHC:FP:00144
CGHC:FP:00144
CGHC:FP:00150
CGHC:FP:00150
CGHC:FP:00150
CGHC:FP:00150
CGHC:FP:00155
CGHC:FP:00155
CGHC:FP:00159
CGHC:FP:00159
CGHC:FP:00160
CGHC:FP:00160
CGHC:FP:00162
CGHC:FP:00162
CGHC:FP:00163
CGHC:FP:00163
CGHC:FP:00175
CGHC:FP:00175
CGHC:FP:0018
CGHC:FP:0018
CGHC:FP:0018
CGHC:FP:00185
CGHC:FP:00185
CGHC:FP:0020
CGHC:FP:0020
CGHC:FP:00217
CGHC:FP:00219
CGHC:FP:00219
Dr Paul O'Brien
Westside Contraceptive Services
Raymede Clinic, Exmoor St, London
W10 6DZ
020 8962 4450 - tel
020 8962 4451 - fax
07900 495 118 - mob
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Philip Ryan
Associate Professor,
Department of Public Health
Associate Dean (Information Technology)
Faculty of Health Sciences
University of Adelaide 5005
South Australia
tel 61 8 8303 3570
fax 61 8 8223 4075
http://www.public-health.adelaide.edu.au/
CRICOS Provider Number 00123M
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