Re: weights for ttest [message #1675 is a reply to message #1674] |
Wed, 26 March 2014 17:59 ![Go to previous message Go to previous message](/theme/default/images/up.png) ![Go to next message Go to previous message](/theme/default/images/down.png) |
Reduced-For(u)m
Messages: 292 Registered: March 2013
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Senior Member |
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Here's one option. Append the two files together. Make separate strata/PSU variables for each survey, and a dummy variable indicating the later survey. Then:
svy: reg HIVOutcome Survey2011
The coefficient on Survey2011 should be the thing you are interested in, assuming you have a continuous measure of some sort. If you want to compare categories it gets a bit trickier, but basically by appending the surveys and using a regression with a dummy for later survey you should be able to use weights and appropriate standard error calculations.
*Note: there is some disagreement here about how to use weights in multiple survey rounds. Weights as given sum to sample size, so I usually standardize weights by survey round (divide the given weight by the sum of weights for that survey round) so that each survey has equal total weight, but that is a preference and shouldn't matter too much.
That sufficient?
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