No Amount of Econometric Sophistication Will Substitute for Good Data
(p. 234) Using a powerful method due to Singh, we have established a relationship between God's attitude toward man and the amount of prayer (p. 235) transmitted to God. The method presented here is applicable to a number of important problems. Provided conditional density (1) is assumed, we do not need to observe a variable to compute its conditional expectation with respect to another variable whose density can be estimated. For example, one can extend current empirical work in a variety of areas of economics to estimate the effect of income on happiness or the effect of income inequality on democracy. We conjecture that this powerful method can be extended to the more general case when X is not observed either.
For the full article, from which the above is quoted, see:
Heckman, James. "The Effect of Prayer on God's Attitude toward Mankind." Economic Inquiry 48, no. 1 (Jan. 2010): 234-35.