Stata: Data Analysis and Statistical Software

It is not that I mind playing  a round with Stata -- on the contrary.
But it migth help us help you, if you could comment on these
statments, elaborate a little bit on the sequence of steps you want to
take here, and maybe be more specific about your ultimate goal. An
example dataset containing all the possibilities you have in mind
would also be nice (only if your first example lacks any possible
situation you want to tackle).

Best
Daniel
-- 
Dear All,

I have this interesting problem where I would have the following dataset -
[...]

I would like to be able to make a flag variable for both the opposite
positive and negative price values for the common make and mpg, while
only keeping one observation if there are duplicates for all make,
price and mpg.

At the same time, if there are 2 duplicated positive price values when
there is one opposite negative price value for the common make and
mpg, I would like to flag one positive price value observation and the
opposite negative price value counterpart. Vice versa would apply if
there are 2 duplicated negative price values and one opposite positive
price value, I would want to flag one negative price value observation
and the opposite positive price value observation.

Expanding on this in the general case,
[...]

Thanks a lot!


Beatrice
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