This is a common listserv item -- the problem is one of precision. Yes,
Stata does store numbers in a different format -- different from decimal --
it's called binary and it's what computers use ;).
If you want to hold 9+ digit numbers accurately they must generated as
doubles (or sometimes longs are long enough). try: gen double id = .....
Given how often this question comes up on the list, I feel that perhaps
StataCorp should consider shipping Stata with double as the default variable
type instead of float.
Michael Blasnik
[email protected]
----- Original Message -----
From: "Tesfayi Gebre" <[email protected]>
To: <[email protected]>
Sent: Monday, June 09, 2003 8:45 AM
Subject: st: Why does Stata do it wrong?
> Dear Statlister,
>
> I want to generate a single unique id to merge files
> by using variables: var1 (F1) var2 (F3) var3 (F4) and
> var4 (F2), where F shows the integer width (f format).
> So, I used
>
> gen id = var1*10^9 + var2*10^6 + var3*10^2 + var4
>
> This is the output from stata and the true id (as it
> should be) for the following
> example:
>
> var1 var2 var3 var4 id (stata) id (true)
> 1 2 3452 1 1005452032 1002345201
> 1 121 34 10 1121033984 1121003410
> 2 23 156 2 2023155968 2023015602
> 2 45 3 2 2045003008 2045000302
> 3 6 4 3 3006003968 3006000403
> 3 70 8 5 3070008064 3070000805
>
*
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