Hi ballardw, Thank you. Yes, this is a two-stage sampling design. However, we are looking at a model where the dependent variable and independent variable is possibly bidirectional. So we would like to use an instrumental variable in the model which does not correlate with the dependent variable but correlates with the independent variable. And thus the reason for performing a 2-stage least squares regression. So I'm wondering whether there is any code available to run a 2-SLS regression with a data set that comes from a two-stage sampling design. Maria
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