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Re: st: Data Corruption?


From   "Svend Juul" <SJ@SOCI.AU.DK>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Data Corruption?
Date   Wed, 24 Oct 2007 09:05:36 +0200

Ed wrote:

I have searched within the archives and cannot find an answer to my
problem. Please correct me if I am missing anything obvious.
I have strange results when calculating (basic) stats for a variable. I
assume there is some sort of data corruption, but I have never seen this
before, so any pointers would be helpful.

Here is a listing of my data (I have added an if condition to keep the
example simple).

. li oil_level gdp if id==211

+-------------------------------+
| oil_le~l gdp |
|-------------------------------|
1059. | 548.9 15492.840168784467 |
1060. | 575.7 16248.206511636326 |
...
1097. | 912.3 34875.37198079319 |
1098. | 948.7 36098.15411932452 |
+-------------------------------+

The listing above is correct and matches the raw data.

Here is a summ of the two series:

. summ oil_level gdp if id==211

Variable     | Obs    Mean  Std. Dev.    Min    Max
-------------+--------------------------------------------------------
oil_level    |  40   781.27  93.45438  548.9  948.7
gdp          |  40  3019.45  771.8664   1673   4237

Note the gdp is obviously wrong. Any ideas?
...
Stata versions: 9.2, both Windows and Linux experience the same problem.

------------------------------------------------------------------------
-

I -input- your data from your listing and generated:
   
    generate id = 211

I can not reproduce your -summarize- output, neither with Stata 10.0 nor
Stata 9.2; I get:

. summarize oil_level gdp if id==211

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
   oil_level |        40      781.27    93.45438      548.9      948.7
         gdp |        40    24624.71    6083.753   15492.84   36098.15

Looks like a human error to me. Are you sure nothing happened to your
data between the -list- and the -summarize- command?

Svend

__________________________________________

Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000  Aarhus C, Denmark
Phone: +45 8942 6090
Home:  +45 8693 7796
Email: sj@soci.au.dk
__________________________________________ 

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