HEURISTIC LOT-SIZING APPROACHES FOR DEALING WITH MRP SYSTEM NERVOUSNESS

We develop and test ways for modifying the Silver-Meal and part-period-balancing lot-sizing procedures to include the costs of schedule changes in response to changes in demand estimates. These modifications tend to reduce MRP system nervousness. We compare the performance of these approaches with the modified Wagner-Whitin algorithm, which we have shown is optimal for static conditions. We find that the modified SilverMeal approach is only slightly more costly than the modified Wagner-Whitin technique and that the modified part-period-balancing approach performs both poorly and erratically.     

UNIVERSITY STARTUP INTENSITY AND FACULTY QUALITY

Using a theoretical model of university technology transfer and licensing survey data from 1991 to 2013, we show that greater faculty quality and venture capital availability is positively associated with licenses to startups. We employ a two‐stage game of licensing terms (royalty rate and fixed fee) and development efforts to show that under reasonable conditions, licensing to a startup rather than an established firm will be more attractive to a technology transfer office (TTO) because the inventor's ownership share in a startup firm will increase total development efforts by the inventor and licensee. TTOs will be more likely to target startup licensees when the marginal effect of the faculty inventor's additional development effort on the probability of success is large relative to that of the venture capitalist or established firm. Empirical evidence supports the results of the model; using Associated University Technology Data licensing survey data and employing panel and cross‐sectional analyses, we show that an increase in the quality of engineering faculty has roughly twice the positive impact on startup licenses than on established firm licenses. Startup licensing is also strongly impacted by venture capital availability within institutions over time. (JEL L24, L26, D86)     

The Long Arm of Trauma During Childhood: Associations with Resources in Couple Relationships

Traumatic experiences within and outside the family of origin in childhood may disrupt couple functioning later in life. Using a sample of 3,958 couples assessed through the Relationship Evaluation Questionnaire (RELATE), an actor–partner independence model was fit to test direct and indirect associations between negative impact from one's family of origin (accounting for physical violence and sexual abuse) and resources in couple relationships. Resources were defined using intervention principles derived from the Conservation of Resources (COR) theory. Actor and partner effects suggested negative family impact associates with relationship instability and is mediated through negative couple communication. Actor effects suggested negative family impact associates with less calmness in one's self and is also mediated through negative couple communication.     

THE EFFECTIVENESS OF EXTENDING THE HORIZON IN ROLLING PRODUCTION SCHEDULING

In recent work, Baker [1] has investigated the use of rolling schedules for multiperiod production scheduling problems. One of his results is that the longest possible forecast horizon is not necessarily the best. He also found that the rolling schedules' effectiveness fluctuates widely depending upon the length of the forecast horizon. To smooth these fluctuations we have investigated use of forecasting to extend the problem horizon. Some of our results confirm the previous conclusions, but other results support the position that “the more information the better.”     

Evaluating the vocational rehabilitation program using longitudinal data. Evidence for a quasiexperimental research design.

The study presents benefit-cost ratios for 14 disability cohorts served by the Vocational Rehabilitation (VR) Program. The earnings impacts are estimated in a quasiexperimental framework using an internal comparison group. The earnings data are from a unique national panel constructed by linking client data of the Rehabilitative Services Administration with earnings histories from the Social Security Administration. These earnings data accommodate a series of statistical tests that allow us to identify and control for the presence of selection bias when estimating treatment impacts. The results indicate that the VR program is cost-effective in general, although not universally so across specific disabilities.     

UNDER THE BRIDGES OF POLK COUNTY:

The obituary was short, to the point. It noted that he was thirty-seven years old, had died of pneumonia at Broadlawns Medical Center, and was survived by a wife, a daughter, his mother, five brothers and two sisters. Nine of the twenty-two lines that appeared on June 1, 1993, in the Des Moines Register reported on demographics about these relatives. Between the middle and last name was inserted, in quotation marks, the word "Wolfman." The information, squeezed in with other similar summaries about other people who had died recently, noted that he was a "self-employed carpenter," that he was from, and his family continued to be in and around, Fort Worth, Texas, and that the services would be at Hamilton's Funeral Home, with burial at Rest-haven Cemetery in West Des Moines.
It is not possible that twenty-two short lines could do justice to thirty-seven years of any person's life. Yet that is what he was allotted. The summer after he died was the summer of the Great Iowa Flood. Wolfman, as everyone called him, never lived to experience the natural event that brought notoriety to the city and devastation to the lives of so many people who shared his community but never knew he existed. I doubt that many people in Des Moines who brushed against his life even knew that his real name was Billy Dean Roberts.     

Generalized linear mixed models: a review and some extensions

Breslow and Clayton (J Am Stat Assoc 88:9–25,1993) was, and still is, a highly influential paper mobilizing the use of generalized linear mixed models in epidemiology and a wide variety of fields. An important aspect is the feasibility in implementation through the ready availability of related software in SAS (SAS Institute, PROC GLIMMIX, SAS Institute Inc., URL , 2007), S-plus (Insightful Corporation, S-PLUS 8, Insightful Corporation, Seattle, WA, URL , 2007), and R (R Development Core Team, R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing, Vienna, Austria, URL , 2006) for example, facilitating its broad usage. This paper reviews background to generalized linear mixed models and the inferential techniques which have been developed for them. To provide the reader with a flavor of the utility and wide applicability of this fundamental methodology we consider a few extensions including additive models, models for zero-heavy data, and models accommodating latent clusters.     

A unified theory for generalized cyclic designs

Properties of abelian groups are used to unify the construction of cyclic and generalized cyclic designs. Necessary and sufficient conditions are obtained for the generation of fractional sets of blocks, and also for the generation of resolvable designs. It is shown how to apply these results in conjunction with efficiency arguments to obtain useful designs.     

An introduction to exponential random graph (p) models for social networks

This article provides an introductory summary to the formulation and application of exponential random graph models for social networks. The possible ties among nodes of a network are regarded as random variables, and assumptions about dependencies among these random tie variables determine the general form of the exponential random graph model for the network. Examples of different dependence assumptions and their associated models are given, including Bernoulli, dyad-independent and Markov random graph models. The incorporation of actor attributes in social selection models is also reviewed. Newer, more complex dependence assumptions are briefly outlined. Estimation procedures are discussed, including new methods for Monte Carlo maximum likelihood estimation. We foreshadow the discussion taken up in other papers in this special edition: that the homogeneous Markov random graph models of Frank and Strauss [Frank, O., Strauss, D., 1986. Markov graphs. Journal of the American Statistical Association 81, 832–842] are not appropriate for many observed networks, whereas the new model specifications of Snijders et al. [Snijders, T.A.B., Pattison, P., Robins, G.L., Handock, M. New specifications for exponential random graph models. Sociological Methodology, in press] offer substantial improvement.     

Stories of AIDS: The use of narrative as an approach to understanding in an AIDS support group

This paper shows how the co-creation and telling of narratives helped members of an AIDS support group transform their unique and separate experiences of suffering into shared insights, intense connections and comfort. Examples of narratives are drawn from the author's experience as a co-leader of a support group for gay men living with AIDS. Current literature on group work with persons living with AIDS is embedded in a modernist orientation in which the therapist is the scientist/expert, the client has the problem and the therapist helps the client's through exploring and interpreting the client's story according to a superseding theory (Gergen and Kaye, 1992). This approach emphasizes the need for leaders to maintain objectivity and emotional distance to avoid burnout (Gabriel, 1991; Grossman and Silverstein, 1993; Tunnell, 1991). In contrast, in a post-modern therapeutic approach, there is no privileging of the therapist's narrative and the traditional hierarchical relationship is replaced by a mutual effort as therapist and client together develop stories that translate and transcend experience. Using the AIDS work as illustration, this paper offers a post-modern, narrative approach to group work and shows how persons living with AIDS can use narrative to move beyond finite structures and the limits of life.This paper couldn't have been written without the help of the group members and my co-leader Sally Bowie. I want to thank them and other friends and colleagues-particularly the members of my Philosophy Study Group for their suggestions and support.The paper is dedicated to the memory of Jack, Paul, Mark, Alex, Richard, Hugh, Stan, Tim, Michael and Bill—all members of the group who have died and to Dean who, though not a member of the group, also died of AIDS and like the others—taught me much about dignity and courage, about being gay and about living with AIDS.