# st: a variable is decreased by 1 ?

 From Gijs Dekkers <[email protected]> To [email protected] Subject st: a variable is decreased by 1 ? Date Mon, 08 Jan 2007 14:05:44 +0100

Dear fellow Stata-users,

I really would appreciate some help with this strange problem...

I have a panel dataset, with the individual number 'pid' and the year variabele 'jaar'. The variable pidnew is an alternative individual-identification number. This variabel, and 'jaar' don't really do anything, but I include it to show that the individual does not changes in what follows.

So, the starting dataset is:

. list pid pidnew jaar if (pid==17025101 & jaar==2002)

+--------------------------+
| pid pidnew jaar |
|--------------------------|
10597. | 17025101 62 2002 |
+--------------------------+

So this is the data line of individual 17025101 in the year 2002. Now I create a copy ('pidold') of this individual identification number,

. gen pidold = pid

. list pid pidold pidnew jaar if (pid==17025101 & jaar==2002)

+-------------------------------------+
| pid pidold pidnew jaar |
|-------------------------------------|
10502. | 17025101 1.70e+07 62 2002 |
+-------------------------------------+

The resulting variable is difficult to read, for it is in the scientific notation. So I change the format...

. format pid pidold epid %14.0f
. list pid pidold pidnew jaar if (pid==17025101 & jaar==2002)

+-------------------------------------+
| pid pidold pidnew jaar |
|-------------------------------------|
10597. | 17025101 17025100 62 2002 |
+-------------------------------------+

And all of a sudden, the variabele 'pidold', which is supposed to be equal to 'pid' has decreased by one! Or, which is more likely, the 'gen pidold = pid' has not done what it should have done, because the format of pidold was set so that information was lost. However, I cannot set a format of a variable prior to its existence.

I have also tried juggling with 'recast' and different formats, but nothing seems to help.

I would really appreciate your help in finding a solution!

Gijs

--
Gijs Dekkers
Attach� Federal Planning Bureau
Research fellow CESO, Katholieke Universiteit Leuven
Kunstlaan 47-49 Avenue des Arts
1000 Brussels, Belgium
phone ++32/(0)2/5077413
fax 7373
skype gdekkers2209
[email protected], [email protected]

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