I would like to know how you proceed with respondents showing so called „extreme response behavior“, i.e. when a respondent always or never chooses the none-option?
A few words about my study first: My study is about electricity tariffs. Therefore, every survey participant uses/purchases this product. I used a pivotal design, i.e. a design where the none-option is displayed as the current product. To describe the current electricity tariff, I use the CBC attributes and levels. I asked for these levels at the beginning of the survey.
To avoid context effects, I separated the forced choice part, i.e. the part without a none-option, and the free choice part, where only the tariff chosen before and the current tariff were displayed. In total, the respondent had to complete 24 choice tasks (12 forced choice sets + 12 free choice sets).
Out of 838 respondents, more than 200 always chose the none-option, i.e. the current electricity tariff. Nearly 40 have never chose the none-option.
Now I am asking myself: What should I do with these responses? I think that I have the the following options:
a) Joint estimation with all data from the free choice tasks
b) Joint estimation, but discard data from the free choice tasks where extreme response behavior occurred
c) Separate models with all data from the free choice tasks
d) Separate models, but discard data from the free choice tasks where extreme response behavior occurred
I doubt that Option a) makes sense in my case. Furthermore, I assume that the cognitive process when deciding to change the electricity tariff (yes/no) is different compared to when someone is forced to choose between different options. Consequently, I have a slight tendency towards options D.
But what do you think? What are your experiences?
I am looking forward to your answers! =)