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Re: st: Deleteing all observations for individuals with anomalousdata


From   Christian Holz <statalist@krueschan.de>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Deleteing all observations for individuals with anomalousdata
Date   Tue, 09 Aug 2005 23:06:59 +0100

Ermmm. Sorry. Next time I think a wee bit more before posting. Of course Nick's command sorts the data set by ID and then by cost within the tied values of ID. And since Stata interprets missings as very large numbers, the missing value (if any) will be last in each group.
Sorry :)

---
Christian Holz
Department of Sociology
University of Glasgow
Scotland, U.K.

Christian Holz wrote:

I think, however, that Nick's approach does not work, if a value for year 5 is there and another year has a missing value, as Nick's command only checks the last observation of each ID group.
I might be wrong, but in case I am not, it's worth mentionning...
Best
---
Christian Holz
Department of Sociology
University of Glasgow
Scotland, U.K.

Nick Cox wrote:


Another way of doing this, without any new variables:
bysort ID (Cost) : drop if missing(Cost[_N])
Nick n.j.cox@durham.ac.uk
Antoine Terracol


I would try something like :

generate tag=(cost==.)
egen toberemoved=sum(tag), by(ID)
drop if toberemoved>0
drop tag toberemoved


You will need to replace the "cost==." in the fisrt line by a more general way to tag your erroneous values (such as "cost==. | cost>9999")

Murray Lowe


I am working with a large dataset and have discovered that

some of the data

are missing values or have erroneous values. The data is

panel data with

observations per individual over a 5 year period. For example:

ID Year Cost

1 1 100
1 2 200 1 3 500
1 4 150
1 5 x
2 1 100 2 2 200 2 3 500
2 4 600
2 5 100

The problem is this: If an individual has a missing /

erroneous value for a

particular year, I want to exclude ALL of their

observations from the

dataset. In the example patient 1 would be removed from the dataset
entirely. How can this be done through an automated-type process?
Essentially I need a code / method that looks for the

anomalous data;

identifies the patient and then removes all of their

observations from the dataset.


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