My work includes the first characterizations of (1) optimal static (simultaneous) search for heterogeneous options, (2) optimal search for multiple homogenous units, and (3) optimal search with selection effects (hidden and observed components)
- Simultaneous Search with Hector Chade (Econometrica, 5-2006)
- Search at the Margin [= The Theory of MultiUnit Search] with Tono Carrasco (forthcoming American Economic Review, 2017)
- Optimal Search Among Alternatives with Michael Choi
En route to writing the last paper, Michael and I wanted to understand when quasi-concavity was preserved under integration. We resolved that, and a larger class of ordinal aggregation results starting with the single crossing property, by realizing the genius of a classic math result of Samuel Karlin:
Ordinal aggregation results via Karlin’s variation diminishing property, Choi and Smith (Journal of Economic Theory, 2016)
We show that the weighted sum of quasiconcave functions is quasiconcave when the (absolute) decreasing part of every function in the sum grows proportionately faster than the increasing part of every function. Here, f grows proportionately faster than g if g is more risk averse than f, in the Arrow-Pratt sense.
Note: Our working paper Ordinal Aggregation Results via Karlin’s Variation Diminishing Property corrects some typos in the published version.