14We have also considered a model in which the CEA equation contains an intercept, h(CEAt) = 𝜃h + 𝜃CEACEAt. In that model 𝜃h is estimated to be insignificant and close to 0. But, as we discuss below, even our reduced model is close to being linear; adding a constant to a nearly linear model only confuses matters. Theoretical considerations suggest that if one of the two linear coefficients should be excluded, it is probably the one for the CEA equation, so we made that choice. Our substantive conclusions are robust to this choice.