If the ids are numeric, then
gen both = string(min(pupil, friend)) + " " + string(max(pupil, friend))
and if they are string, then
gen both = cond(pupil < friend, pupil, friend) + " " + cond(pupil < friend, friend, pupil)
Now search for -duplicates- on both.
Suppose "Tony" names "Gordon" as his best friend, and vice versa.
It is true that "Gordon" < "Tony" as inequalities with strings are
based on alphanumeric order.
Either way,
pupil friend
42 24
24 42
will both be mapped to "24 42"
and
pupil friend
Tony Gordon
Gordon Tony
will both be mapped to "Gordon Tony". Then, as said, look for
-duplicates-.
Nick
[email protected]
Phillip Sinclair PhD (Lond) MSc BSc
> I have a data list of the following form:
>
> 1. pupil id ... friend id
> 2. pupil id ... friend id
> 3. etc
>
> Each pupil can have several friends, each listed as a
> separate case i.e. there can be several cases with the same
> pupil id each case identifying a separate friend.
> I wish to create a new variable to identify reciprocated
> friendship choices e.g. where pupil A names pupil B as a
> friend and pupil B names pupil A as a friend.
> Please can you tell me of a simple way of doing this in STATA.
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
