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Two or Three Sampling Stages [message #1710] Tue, 01 April 2014 14:13 Go to previous message
lukassg is currently offline  lukassg
Messages: 12
Registered: January 2014
Member
Hey!

Could someone explain me exactly what is the difference between three-stage and two-stage sampling?

I very well understand the two-stage sampling:

1. I select a certain number of enumeration areas based on a previous census or national survey.
2. I sample a certain number of households from these EAs/clusters.

For the three-stage sampling:

As I understand it, this stage is before the EAs/clusters are selected. So we have even larger areas in the first stage, from which we then select the EAs/clusters in the second stage and the households in the third stage? Why do we have this additional stage in the beginning?

Finally, I am pooling always two different DHS survey for one country to get an over-time estimator of certain effects. I know that I have to adapt the stratification and PSU specifications. Is that enough in the case of a country, e.g. Tanzania, where I pool the years 1999 and 2010, where one year has 3 stages and the other 2 stages? Or does that make it impossible to analyse?

In this context, I also stumble upon probability proportional to size (pps). Can someone explain me this concept as well? :)

Thanks for your help!

Lukas

[Updated on: Tue, 01 April 2014 15:07]

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