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RE: st: repeated values of a variable
That often used to happen. But now it is very
easy to ensure that ados leave the data in
the original sort order (unless of course
it is an explicit purpose of the ado that
the sort order will be changed).
This is all explained clearly and concisely by Roger
Newson, R. 2004. Stata tip 5: Ensuring
programs preserve dataset sort order.
Stata Journal 4(1): 94.
The following guidelines have been suggested
in -stylerules- on SSC. Strictly, these are
my style rules, and others should publish
Respect for datasets
In general, make no change to the data unless that is the
direct purpose of your program or that is explicitly
requested by the user. For example,
your program should not destroy the data in memory
unless that is essential for what it does
you should not create new permanent variables on
the side unless notified or requested
do not use variables, matrices, scalars or global
macros whose names might already be
in use: there is absolutely no need to guess at
names unlikely to occur, as temporary names can
always be used (see help on tempvar, tempname, and tempfile)
do not change the type of a variable unless requested
do not even change the sort order of data: programs
can easily be made sortpreserve.
> In general, data sets should have id numbers;
> sort commands
> can be a little scary without them, and ado files may sort your data
> without your knowledge. It would be sort of a shame if you
> had thousands
> of survey questionnaires coded and then couldn't link the
> data back to
> their original sources.
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