Background In a small online study I asked people (n=100) which products they would purchase. The choice set contained 20 products for which they had to indicate whether they would buy a product or not (= DV, yes/no format). Respondents could indicate yes for any number of products. The IVs were product and presentation characteristics.
Data format resp_id (in rows), buy_prod_1, buy_prod_2 ... and IVs in columns
Previous analyses I did a “simple” logistic regression in Stata. For this I reshaped my data so that there is one line for each respondent and each product (100*20 lines, buy_prod and IVs in columns). In the logistic regression buy_prod was my DV.
Problem I do not know how to integrate the fact that the product choices for each respondent are not independent, i.e. how to combine the different DVs in the right way in one model.