The data comes from a large international organization and they did not publish their methodology, but shared the data publicly with weights that adjust for over- /under-sampling by age, education, income, etc. . The survey was implemented in several countries and the weights try to ensure that the data from each country are representative of that country. This is all I know. I am aware that it is likely not possible to appropriately estimate the variance and std errors using the available info. I do not yet have a model as I am in the process of determining which method and sas procedure to use. The data is clustered at the country level (i.e, respondents from the same country are more likely to be similar), I assume, hence the need to take clustering into consideration when fitting the model.
