A stated choice experiment to measure the effect of informational and normative conformity in the preference for electric vehicles

This work aims to measure the effect of both informational and normative conformity in the preference for electric vehicles (EV) versus internal combustion vehicles (ICV). Differently from most of the literature in the field, measures of conformity are included as attributes inside a stated choice (SC) experiment, allowing a direct comparison of their effects with typical effects such as purchase price, range and fuel/electricity price. To measure informational conformity we set up an experiment where the same individual answers the choice tasks before and after he/she has received social information on three specific EV features: range, parking spaces reserved for EV and the need to change activity schedule if using an EV. Normative conformity was measured in terms of social adoption, social-signalling and injunctive norms. Social adoption and a pair of eyes to detect social-signalling were included as attributes in the stated choice experiment, while injunctive norms were measured using psychometric indicators. The SC experiment was also aimed at testing the effect of parking policy on the choice of EV. Hybrid choice models were estimated and a resampling technique was used to test the model sensitivity to the sample gathered. All social conformity effects tested are highly significant and their impact in the overall utility can be high enough to compensate also quite low driving range for EV (e.g. around 130 km) or significant differences in purchase price (for example 1/3 higher for EV than ICV). We also found that parking price and the number of slots reserved for EV can be effective in boosting the demand for EV, but a combination of parking policies is needed because each measure alone does not have a sufficient impact to compensate major differences in the characteristics between EV and ICV.