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RE: st: can GLLAMM handle missing data?
From
"Pesola, Francesca" <[email protected]>
To
"[email protected]" <[email protected]>
Subject
RE: st: can GLLAMM handle missing data?
Date
Thu, 27 Mar 2014 13:25:28 +0000
Hi David,
Thanks again for your helpful input. I will get hold of the book you recommended.
Cheers,
Francesca
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Hoaglin
Sent: 26 March 2014 15:24
To: [email protected]
Subject: Re: st: can GLLAMM handle missing data?
Hi, Francesca.
I have no simple answer. What you should do depends on the extent, pattern, and nature of the missingness. All I know about your data so far (I think) is that you have repeated measures for respondents at 7 time points. From the number of level-2 units (566) and the number of
level-1 units (2284), it appears that you have a substantial number of missing observations (566 x 7 - 2284 = 1678).
I suggest that you start by examining the patterns of missing observations and considering the possible reasons for the missingness.
It will be important to understand those reasons in as much detail as possible, to determine whether the observations that are missing are "missing completely at random," "missing at random," or "missing not at random." (More than one of these categories may apply.) The information on the nature of the missingness will affect how you interpret results from -gllamm-, and it will also guide choices that you will need to make if you use multiple imputation. Don't underestimate the amount of work that you may need to do before you proceed with any analysis. Considerable judgment is involved, and the process cannot be automated.
David Hoaglin
On Wed, Mar 26, 2014 at 9:15 AM, Pesola, Francesca <[email protected]> wrote:
> Hi David,
>
> Thank you very much for your helpful reply.
>
> Do you think as good practice I should:
>
> 1. Run the analysis with the missing data and rely on the GLLAMM
> flexibility; and
>
> 2. Impute the data using MI as sensitivity analysis
>
> Thanks,
> Francesca
>
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