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Home » Data » Dataset use in Stata » Poolled logistic regression (Poolled logistic regression (three surveys for one country))
Poolled logistic regression [message #29861] Wed, 14 August 2024 09:37 Go to next message
gwasswa is currently offline  gwasswa
Messages: 4
Registered: March 2024
Member
Hello there,

Could anyone guide me on how to do this?
I want to estimate a pooled logistic regression of three surveys appended to each other but for one country. Through reading on the existing chats i realise there could be an issue with how to weight the pooled data set. Could anyone advise on how to normalise the weights? One of the chats suggest this as a possible solution. Another question is, since there are three surveys then i would expect to include two dummy variables for two of the three survey years. Is there anything else i have to do to ensure accurate results? I will appreciate your help.

Gabriel
Re: Poolled logistic regression [message #29870 is a reply to message #29861] Thu, 15 August 2024 10:02 Go to previous messageGo to next message
Bridgette-DHS is currently offline  Bridgette-DHS
Messages: 3201
Registered: February 2013
Senior Member

Following is a response from Senior DHS staff member, Tom Pullum:

Yes, you need a variable such as survey=1, 2, 3, which I easily constructed during the appending process. In the analysis you can treat "survey" as a categorical predictor or convert it to dummies.

We recommend that you leave the weights as they are. You only need to adjust the weights if you want to construct a pooled estimate of something, for example the median age at first marriage, and I really don't believe such an pooled estimate has any value. The main reason for appending surveys from the same country is to see whether there has been significant CHANGE between surveys, and for that purpose you should leave the weights alone. If you do that, the analysis will weight each survey in proportion to its sample size, and for efficient statistical estimation that's what you want.
Re: Poolled logistic regression [message #29874 is a reply to message #29870] Thu, 15 August 2024 11:22 Go to previous messageGo to next message
gwasswa is currently offline  gwasswa
Messages: 4
Registered: March 2024
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Thanks to you both, Bridgette and Tom.

This is helpful and good to know. just another thing I would like to ask, do I still have to keep using svy:... command in the regression? Many thanks.
Re: Poolled logistic regression [message #29875 is a reply to message #29874] Thu, 15 August 2024 13:01 Go to previous messageGo to next message
Bridgette-DHS is currently offline  Bridgette-DHS
Messages: 3201
Registered: February 2013
Senior Member

Following is a response from Senior DHS staff member, Tom Pullum:

Yes, but you need to construct unique cluster ID codes and stratum ID codes for the three surveys, using "egen group". Please look through previous posts for an explanation.
Re: Poolled logistic regression [message #29879 is a reply to message #29875] Thu, 15 August 2024 14:32 Go to previous message
gwasswa is currently offline  gwasswa
Messages: 4
Registered: March 2024
Member
Thanks Bridgette,

Yes, I will.
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