RE: st: repeated time values within panel

["Momplaisir, Florence" <Florence.Momplaisir@tuhs.temple.edu>]

Thanks for your response Nick. My understanding is that adding the time variable tells stata that the order of observations within the panel matter i.e. that there is a time order (here baby year of birth) within the panel. This is important because moms with multiple babies can have controlled HIV disease on their first pregnancy but not on their second or third pregnancies.
________________________________________
From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] on behalf of Nick Cox [njcoxstata@gmail.com]
Sent: Thursday, September 05, 2013 10:50 AM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: repeated time values within panel

Backing up here: What is your reason for setting a time variable here?
Clearly your mothers define panels, but  different mothers have
children at quite different times. -xtset Stateno- may be as much as
you really need. Nothing stops you using the year as a covariate for
most other purposes. Which commands do you want to run that require a
time variable to be set?

Nick
njcoxstata@gmail.com


On 5 September 2013 15:37, Momplaisir, Florence
<Florence.Momplaisir@tuhs.temple.edu> wrote:
> Hello,
>
> I'm working with a longitudinal dataset using surveillance data on HIV+ women during pregnancy and at delivery. In the dataset, women have multiple pregnancies and some have multiplets (twins, triplets etc). I'm using the xtset command to run a regression with the woman (Stateno variable) and the year as the time variable. Here is the error I found:
>
> xtset Stateno birthyr
> repeated time values within panel
> r(451);
>
> And this is because I have twins that have repeated time values, i.e. repeated time measures. How do I get ride of that duplicate without deleting from the dataset?

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