counting the number of times individual appears more than once

Hi there, I have an interesting database of what I thought was 11000 clients. Turns out for my person identifier variable I have the same individual reported more than once (I noticed when I sorted). when there is a duplicated the same info is recorded in the columns. Is there a way of counting how many times I have the same individual more than once so that I can know really how many people I have in the dataset.

Also when they appear more than once is there a way of deleting the duplicate observations?

Thanks in advance



Take a look at the -duplicates- command, the -codebook- command (which tells you the number of unique observations for a given variable), and this old but still informative FAQ.
if the identifier for each person does not change, you can easily get the number of UNIQUE person in your dataset
bys ID: gen junk=_n
gen pernd=junk==1
tab pernd
**pernd means person identifier

Then, if each row means one visit you do:
gen visit=1
egen tot_visit=sum(visit), by (ID)
and this will give you the sum of the times (rows) the person has apparead