Three essays on the economics of information systems

With the rapid development of computing devices and the improved Internet access, our daily lives and business world have been dramatically reshaped. While technology allows companies to attain unprecedented efficiency gains, it also brings about fundamental changes to the competition environment. The goal of this dissertation is to improve our understanding of three major technological developments through the lens of applied economics, econometrics, and machine learning. The first chapter is on the mobile application (app) market. The mobile app market is a fast growing platform which offers consumers millions of applications for smartphones and tablets, but the astronomical number of apps creates a search and discovery problem. I propose an optimal matching for a new advertising strategy, "Cross Promotion (CP)," which allows app developers to locate valuable users while helps app users discover new apps. Distinct from the extant platform literature, which consists mostly of theoretical formulations of platforms, I develop a two-stage model using data from a random matching experiment to examine how users preferences are influenced by apps characteristics. I propose a matching scheme which significantly improves the effectiveness of the CP using the deferred acceptance algorithm. The second chapter is on the issue of cybersecurity. I propose a potential information disclosure policy to alleviate cybersecurity threats. With a large-scale randomized field experiment consisting of 7,919 organizations in the U.S., I show through a random forest-assisted heterogeneous treatment effect analysis that the combination of information notification and publicity significantly reduces large spammers outbound spam volume, which is an indicator of an organizations underlying security condition. The last chapter investigates social media platforms, which is on companies social media strategies under challenging situations. Through a theoretical model, the use of support vector machine, and an empirical analysis using a large Twitter data set, I show the existence of both a negative spillover and a customer encroachment effect after the airline industrys major product-harm crises. In addition, I show that non-focal companies appear to harness two distinct functions of social media-offensive and defensive marketing strategies-to alleviate the negative influence and exploit the unexpected benefit as a result of such incidents.Economic