UC Berkeley

My thesis consists of three essays in the field of operations management and marketing.

In the first essay, I study the problem of consumer search for information on multiple products. When a consumer considers purchasing a product in a product category, the consumer can gather information sequentially on several products. At each moment the consumer can choose which product to gather more information on, and whether to stop gathering information and purchase one of the products, or to exit market with no purchase. Given costly information gathering, consumers end up not gathering complete information on all the products, and need to make decisions under imperfect information. I solve for the optimal search, switch, and purchase or exit behavior in such a setting, which is characterized by an optimal consideration set and a purchase threshold structure. It is shown that a product is only considered for search or purchase if it has a sufficiently high expected utility. Given multiple products in the consumer's consideration set, the consumer only stops searching for information and purchases a product if the difference between the expected utilities of the top two products is greater than some threshold. Comparative statics show that negative information correlation among products widens the purchase threshold, and so does an increase in the number of the choices. Under my rational consumer model, I show that choice overload can occur when consumers search or evaluate multiple alternatives before making a purchase decision. I also find that it is optimal for sellers of multiple products to facilitate information search for low-valuation consumers, while obfuscate information for those with high valuations.

In the second essay, I conduct an empirical study of peer effects of iPhone adoptions on social networks. I use a unique data set from a provincial capital city in China, in a span of over four years starting from iPhone's first introduction to mainland China. I construct a social network using six month's call transactions between iPhone adopters and all other users on a carrier's network. Strength of social ties is measured by duration of calls. Based on the network structure, I test whether an individual's adoption decision is influenced by his friends' adoptions. A fixed-effect model shows that, on average, a friend's adoption increases one's adoption probability in next month by 0.89%, and the marginal effect decreases in the size of his current neighboring adopters. To further control for potential time-varying correlated unobservables, I instrument adoptions of one's friends by their birthdays, based on the fact that consumers are more likely to adopt iPhones on birthdays. The IV estimation shows a slightly smaller peer effect at 0.75%. I also investigate how network structures modulate the magnitude of peer influence. My results show that peer effect is stronger when the influencer has more friends or has a stronger relationship with the influence.

In the third essay, I study the problem of coordination of operations and marketing decisions for new product introductions. In the industry with radical technology push or rapidly changing customer preference, it is firms' common wisdom to introduce high-end product first, and follow by low-end product line extensions. A key decision in this "down-market stretch" strategy is the introduction time. High inventory cost is pervasive in such industries, but its impact has long been ignored during the presale planning stage. This essay takes a first step towards filling this gap. I propose an integrated inventory (supply) and diffusion (demand) framework, and analyze how inventory cost influences the introduction timing of product line extensions, considering substitution effect among successive generations. I show that under low inventory cost or frequent replenishment ordering policy, the optimal introduction time indeed follows the well-known "Now" or "Never" rule. However, sequential introduction becomes optimal as the inventory holding gets more substantial or the product life cycle gets shorter. The optimal introduction timing can increase or decrease with the inventory cost depending on the marketplace setting, requiring a careful analysis.