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Re: st: filling in the gaps

From   Maarten Buis <>
Subject   Re: st: filling in the gaps
Date   Fri, 18 Jan 2013 10:14:41 +0100

--- Am 18.01.2013 09:21, schrieb John Singhammer:
>> I'm working on a dataset consisting of information on 45.000 school
>> children Data has been collected annually since 2009, though not
>> for all children Information on grade has been imported from a
>>  national register. However, that information is only available up to
>> the year 2011

--- On Fri, Jan 18, 2013 at 9:44 AM, Jan Ditzen wrote:
> if I understood your problem correctly the following should help:
> by id (sch_year), sort: replace grade = grade[_n-1]+1 if grade == .

Technically that is true, but statistically that is typically bad
practice. This way you impose a very severe pattern on the grade
profiles of those kids. If that is what you want to study, than any
subsequent analysis is no longer empirical research but just
reproducing your assumptions.

In general I would say that if you only have data on a key variable
till 2011, than that is it: you have data till 2011 and no more. If
you really really need those subsequent years and you really really
cannot wait till those data become available than you could try
multiple imputation (type in Stata -help mi-). However, given the fact
that these are complete years that are missing I would strongly
recommend against that. Instead I would just stick to the years
2009-2011 and in a couple of years, when the data for 2012 and 2013
become available, write a new article for the period 2009-2013.

-- Maarten

Maarten L. Buis
Reichpietschufer 50
10785 Berlin
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