Regier DA, Sicsic J, Watson V. Choice certainty and deliberative thinking in discrete choice experiments. A theoretical and empirical investigation. J Econ Behav Organ. 2019 Aug;164:235-55. doi: 10.1016/j.jebo.2019.05.031
Mansfield CA. A consistent method for calibrating contingent value survey data. South Econ J. 1998;64(3):665-81.