Based on my contingent valuation survey (double-bounded dichotomous choice), I have decided to run the models (e.g. Model 1: WTPa; Model 2: WTPb; Model 3: WTPc, and WTPmax) for only positive response. The question is how can I run these models separately?

The dependent variable is dichotomous WTP response (e.g. WTPa-first answer for offered price; WTPb- second answer for next question...). While the independent variables are sociodemographic info (e.g. age, income, occupation, etc.).

Should I separate first the data into a different model? Then, the problem is what is the dependent variable? Because there is only one answer (e.g. Yes).