This Dissertation combines methodological and applied papers on computational Economics, Industrial Organization and Education. The first chapter develops a new computational approach to inverting a Pure Characteristics Model of demand. It shows how to use first order information of mapping from structural parameters to predicted market shares to reliably invert the system of market shares equations. This new algorithm significantly improves performance of the inversion and may prove useful for empirical analysis of single product demand as the Pure Characteristics Model is an attractive alternative to Mixed Logit demand model in many applications. The second chapter looks at inventory management problem of a store manager. It shows that if a store manager has to keep stock of products to meet demand and he has a cost of stocking each particular product, he will choose to not offer some varieties that would have been supplied by central planner maximizing social welfare. Thus, because manager's incentives are mis-aligned with society, there will always be under-supply of variety. The welfare loss of it is moderate since the varieties that are not offered are the ones with weakest demand. The third chapter develops a new approach to estimate the distribution of cardinal preferences for university programs from strategic reports. As applicants misrepresent preferences, the primary challenge is obtaining an estimate of the true preferences from the observed submitted ones. To do this, we propose an estimation strategy based on revealed preference. We assume that each applicant has one of a finite set of preferences and, unlike the usual logit approach, there is no random element to preferences. Thus, each applicant belongs to a preference group, all members of which have exactly the same preferences. We estimate the cardinal utilities associated with each preference group, along with its prevalence in the population. Using our estimates we are able to predict the equilibrium effects of policy changes to the Turkish university placement mechanism. We predict that an affirmative action policy that gives low-income applicants a one standard deviation benefit in terms of acceptance cutoffs improves their expected utility by 69%, which is less than a third of what using a standard logit setup would predict. Our approach is flexible and can be scaled to very large problems because we re-cast the estimation problem as a large sequence of linear programs, as opposed to a large scale non-linear optimization problem.