Fig. 1

Basic idea of the SPADE 2-part models. Legend: The panel on the left (a) shows the SPADE 2-part model without the inclusion of the information on the never-consumers. The panel on the right (b) shows the SPADE 2-part model with the inclusion of the information on the never-consumers. Note that based on the FFQ information the population is divided into the consumers and non-consumers on one hand; and the never-consumers on the other hand [21, 22]