“…Paying for randomly selected questions is incentive compatible under Expected Utility, but not necessarily under more general risk preferences, where it is known that no such mechanism may exist(Karni and Safra, 1987;Azrieli et al, 2018). An old and still growing literature suggests this theoretical concern may not be empirically important(Beattie and Loomes, 1997;Cubitt et al, 1998;Hey and Lee, 2005;Kurata et al, 2009), but there are some exceptions(Freeman et al, 2015). Dynamic designs are generally not incentive compatible, however in practice this is of little concern-see Appendix A.19 The conversion from points to awards can only be done at specific point values, which leads to a slightly convex payoff schedule.…”