In repeated choice modelling studies, it is often the case that individuals always select the status quo option. Although this pattern may reflect considered choices, they may also be the result of alternative decisions about whether to participate in the choice process at all. Alternative methods of dealing with this behaviour, each with associated implications for estimates of economic values, are presented. In particular we consider the alternative strategies of excluding such individuals from the data, using hurdle models to explicitly model this group, and propose the use of latent class models to endogenously allow for different preference structures. An advantage of the latent class approach is that the form of the non-participation need not be defined in advance. These approaches are considered using UK choice experiment data on food choices where the attributes include genetic modification of food. The latent class approach reveals the presence of two forms of non-participation in the data.