http://hdl.handle.net/1721.1/7728 http://hdl.handle.net/1721.1/47833 Phantom work : design iteration timing in new product development McCarthy, Daniel J. (Daniel Joseph) As companies compete to gain market share, increase profits and affect growth they often turn to concurrent engineering in an effort to bring new products to the market more quickly. Despite many anecdotal success stories, implementation of concurrent engineering can often prove difficult. As the pressure to bring new products to market increases, companies often compress their design iteration cycle times in an effort to develop products more quickly. In many cases, design cycles may overlap creating situations where learning opportunities (e.g. through testing) are missed and/or ignored. More perversely, compressing design iteration cycles can cause the creation of "phantom errors" and unnecessary rework as concurrent design activities iterate at different speeds. In this research, I use a system dynamics approach to develop a stylized simulation model of the design-build-test iteration cycle to explore the effects of cycle timing on learning. Specifically, I look at the frequency and timing of integration (build) test events and their effect on new product delivery time, quality, and development cost. This research adds to the existing literature in new product development, concurrent engineering, and system dynamics. Ultimately, the results serve to inform new product development project managers of the implications of design iteration timing on project performance and assist in the scheduling of integration events. Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 2008. Includes bibliographical references (p. 288-290). http://hdl.handle.net/1721.1/47832 Recommendations, credits and discounts : essays in behavioral decision making Maciejovsky, Boris Essay 1: Translation Errors in the Aggregation of Consumer Recommendations There has been a substantial increase of websites providing consumers with recommendations about products and services. These recommendations are usually presented in the form of verbal reviews and numerical ratings. It is assumed implicitly that consumers can integrate adequately the information across the two presentation modes (verbal and numerical). However, research on the effects of compatibility between stimulus and response formats suggests that preference consistency is higher (lower) in cases of compatible (non-compatible) formats, implying that information aggregation across the two modes may be sub-optimal. The results of three experiments confirm this conjecture. Information aggregation and preference reversals were systematically affected by the compatibility of the stimulus and response format. Decision makers were not aware of this effect. Essay 2: The Researcher as a Consumer of Scientific Publications: How Do Name Ordering Conventions Affect Inferences About Contribution Credits? When researchers from different fields with different norms collaborate, the question arises how name ordering conventions are chosen, and how they affect contribution credits. In this paper we answer these questions by studying two disciplines that exemplify the two cornerstones of name ordering conventions: Lexicographical ordering (i.e., alphabetical ordering, endorsed in economics) and non-lexicographical ordering (i.e., ordering according to individual contributions, endorsed in psychology). Inferences about credits are unambiguous in the latter arrangement, but imperfect in the former, because alphabetical listing can reflect ordering according to individual contributions by chance. We contrast the fields of economics and psychology with marketing, a discipline heavily influenced by both. (cont.) Based on archival data, consisting of more than 38,000 journal articles, we show that the three fields have different ordering practices. In two empirical studies, with 351 faculty and graduate student participants from all three disciplines, as well as in a computer simulation, we show that ordering practices systematically affect and shape the allocation of perceived contributions and credit. While strong disciplinary norms in economics and psychology govern the allocation of contribution credits, a more heterogeneous picture emerges for marketing. This lack of strong norms has detrimental effects in terms of assigned contribution credits. Essay 3: Performance-Contingent Discounts and Consumer Choice Incentives affect individuals' attitudes and behaviors in a myriad of ways. In this paper we explore the effects of performance-contingent discounts on consumer choice. For that purpose we set up an online store for digital cameras. Half the subjects received a fixed rebate; the other half had to "earn" their rebate by learning about the products offered. The more information subjects remembered, as inferred from their answers to a short quiz, the higher their discounts. Our results indicate that subjects, who were offered performance-contingent discounts, found the online store more informative and reputable, were more likely to recommend the store to their friends, and were more likely to buy. The results cannot be attributed to a better performance in the quiz or a more thorough exploration of the products offered. Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 2009. Includes bibliographical references. http://hdl.handle.net/1721.1/46661 Combinatorial optimization problems with concave costs Stratila, Dan In the first part, we study the problem of minimizing a separable concave function over a polyhedron. We assume the concave functions are nonnegative nondecreasing on R+, and the polyhedron is in RI' (these assumptions can be relaxed further under suitable technical conditions). We show how to approximate this problem to 1+ E precision in optimal value by a piecewise linear minimization problem so that the number of resulting pieces is polynomial in the input size of the original problem and linear in 1/c. For several concave cost problems, the resulting piecewise linear problem can be reformulated as a classical combinatorial optimization problem. As a result of our bound, a variety of polynomial-time heuristics, approximation algorithms, and exact algorithms for classical combinatorial optimization problems immediately yield polynomial-time heuristics, approximation algorithms, and fully polynomial-time approximation schemes for the corresponding concave cost problems. For example, we obtain a new approximation algorithm for concave cost facility location, and a new heuristic for concave cost multi commodity flow. In the second part, we study several concave cost problems and the corresponding combinatorial optimization problems. We develop an algorithm design technique that yields a strongly polynomial primal-dual algorithm for a concave cost problem whenever such an algorithm exists for the corresponding combinatorial optimization problem. (cont.) Our technique preserves constant-factor approximation ratios as well as ratios that depend only on certain problem parameters, and exact algorithms yield exact algorithms. For example, we obtain new approximation algorithms for concave cost facility location and concave cost joint replenishment, and a new exact algorithm for concave cost lot-sizing. In the third part, we study a real-time optimization problem arising in the operations of a leading internet retailer. The problem involves the assignment of orders that arrive via the retailer's website to the retailer's warehouses. We model it as a concave cost facility location problem, and employ existing primal-dual algorithms and approximations of concave cost functions to solve it. On past data, we obtain solutions on average within 1.5% of optimality, with running times of less than 100ms per problem. Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2009. Includes bibliographical references (p. 83-89). http://hdl.handle.net/1721.1/46387 Mitigating airport congestion : market mechanisms and airline response models Harsha, Pavithra Efficient allocation of scarce resources in networks is an important problem worldwide. In this thesis, we focus on resource allocation problems in a network of congested airports. The increasing demand for access to the world's major commercial airports combined with the limited operational capacity at many of these airports have led to growing air traffic congestion resulting in several billion dollars of delay cost every year. In this thesis, we study two demand-management techniques -- strategic and operational approaches -- to mitigate airport congestion. As a strategic initiative, auctions have been proposed to allocate runway slot capacity. We focus on two elements in the design of such slot auctions -- airline valuations and activity rules. An aspect of airport slot market environments, which we argue must be considered in auction design, is the fact that the participating airlines are budget-constrained. -- The problem of finding the best bundle of slots on which to bid in an iterative combinatorial auction, also called the preference elicitation problem, is a particularly hard problem, even more in the case of airlines in a slot auction. We propose a valuation model, called the Aggregated Integrated Airline Scheduling and Fleet Assignment Model, to help airlines understand the true value of the different bundles of slots in the auction. This model is efficient and was found to be robust to data uncertainty in our experimental simulations. (cont.) -- Activity rules are checks made by the auctioneer at the end of every round to suppress strategic behavior by bidders and to promote consistent, continual preference elicitation. These rules find applications in several real world scenarios including slot auctions. We show that the commonly used activity rules are not applicable for slot auctions as they prevent straightforward behavior by budget-constrained bidders. We propose the notion of a strong activity rule which characterizes straightforward bidding strategies. We then show how a strong activity rule in the context of budget-constrained bidders (and quasilinear bidders) can be expressed as a linear feasibility problem. This work on activity rules also applies to more general iterative combinatorial auctions.We also study operational (real-time) demand-management initiatives that are used when there are sudden drops in capacity at airports due to various uncertainties, such as bad-weather. We propose a system design that integrates the capacity allocation, airline recovery and inter-airline slot exchange procedures, and suggest metrics to evaluate the different approaches to fair allocations. Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2009. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Includes bibliographical references (leaves 157-165).