The original question
> > > > I have a dataset which has customer's payment amount by month
> > > > by year. Month
> > > > ranges from 01 to 12 for years 2000 & 2001 and from 01 to 09
> > > > for the 2002. But
> > > > all customers don't have data for each month. The dataset
> > > > looks like the
> > > > following.
> > > >
> > > > customer month year amount
> > > > x1 01 2001 50.45
> > > > x1 03 2001 60.00
> > > > x2 04 2001 70.00
> > > > x2 06 2001 80.00
> > > >
> > > > I would like to create a data set where each customer
> will have 12
> > > > observations for years 2000 & 2001 and 9 obs. for 2002, and
> > > > amount will be
> > > > zero for the months they don't have any original data. I
> > > > tried with couple of
> > > > different ways, but didn't work. Could anyone please help me?
Nick Winter
>
> Oops.
>
> I misread the question. There are clearly better ways to
> do this, than
> to use -reshape-.
Not so fast! I don't see it as that clearcut.
This is a nice problem, and there are points about
Stata technique which make it of wider interest.
As I write, three solutions have been
proposed, here summarised in order of
first posting, and with second thoughts
written in.
1. Nick Winter
==============
-reshape wide- followed by -reshape long-.
This is a good general procedure. Other
applications abound.
It is not going to fill in all gaps.
Empirically, my guess is that is
not a problem.
If it is, then a little preparation
will fix the problem. It is necessary
and sufficient that all times be
present for at least one customer.
2. Nick Cox
===========
-fillin-.
-fillin- is optimised for this one
problem. It does nothing else. Perhaps
you never heard of it. There is always
a problem learning of and remembering
tools you use only once in a while.
It is better to learn about more
general tools.
It is not going to fill in all gaps.
Empirically, my guess is that is
not a problem. Same comment
as above (and one method was
proposed).
3. Tao Jiang
============
-merge- with a complete data set.
No code presented, but in principle
this sounds elegant. You could
-contract- on -customer- and then
-expand- and create a time variable.
-merge- is a very good general procedure.
Other applications abound.
Naturally, getting one solution
that works is enough. But there is
a lot of evidence that different
Stata users find different tools
intuitive, so choose whatever
appeals.
Nick
[email protected]
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