ON THE INDEPENDENCE OF THE SAMPLE MEAN AND TRANSLATION-INVARIANT STATISTICS FOR MATRIX NORMAL DISTRIBUTIONS

We present an explicit characterization of the joint dependency structure of an n×p matrix normal random matrix such that the p-dimensional sample mean vector is independent of all translation invariant statistics.     

Optimal Times to Contact Sample Households

Finding a suitable respondent at home is an essential and expensivecomponent of a household survey. This article reports on theresults of a study of the probabilities of finding someone aged14 or older at home and discusses the application of such datato survey design and budgeting.     

An evaluation of the tandem configuration automated guided vehicle system

The performance of a tandem automated guided vehicle (AGV) system is compared with that of conventional AGV track systems. In the tandem system the track is divided into non-overlapping, single-vehicle closed loops. Using simulation it is shown that, because of trips requiring delivery across loops, the tandem system has a higher expected travel time per load and thus a greater average time in system. When the loads are delivered within the original loop only, the tandem system has a lower average time in system than in conventional systems, although the difference is modest. Track layout appears to influence the average time in system much more than docs the dispatching rule invoked. The success of the tandem system is highly dependent on approximately even AGV utilization, which may be difficult to obtain in practice.     

ABORTION AND CRIME: UNWANTED CHILDREN AND OUT-OF-WEDLOCK BIRTHS

Legalizing abortion can either increase or decrease investments in children's human capital. This article finds that abortion increases the number of out-of-wedlock births. Using data that more directly links the criminal with age when the crime was committed, not age when arrested, and fixing the assumption in previous research that no abortions took place prior to the Roe v. Wade decision in the 45 states affected by that decision, we find consistent significant evidence that legalizing abortions increased murders by over 7%. Linear estimates indicate that legalization increased total annual victimization costs by at least $3.2 billion. ( JEL K42, K14, J24)     

Mixing patterns between age groups in social networks

We present a method for estimating transmission matrices that describe the mixing and the probability of infection between age groups. Transmission matrices can be used to estimate age-dependent forces of infection in age-structured, compartmental models for the study of infectious diseases. We analyze the social network generated by the synthetic population of Portland and extract mixing patterns. Our results show that the mixing within the population consists of two groups, children and adults. Children interact most frequently with other children close to their own age, while adults interact with a wider range of age groups and the durations of typical adult contacts are shorter than typical contacts between children. Furthermore, the transmission matrix shows that children are more likely to acquire infection than adults.     

Television Coverage of State Government

An empirical analysis of 3,334 state and local television newsstories in 10 cities clarifies the reluctance of commercialtelevision newscasters to cover state government. Contrary towhat many television news directors assert, television's minimalattention to state government cannot be attributed to an allegednegative relationship between state government and newscastratings. Rather, it appears to stem from the high cost of obtainingfilmed coverage of state government in a timely fashion.     

Training in Human Relations Skills as a Preferred Mode of Treatment for Married Couples*

While effective communication is recognized as important to marital adjustment, few therapeutic alternatives specifically attempt to teach improved communication skills in a systematic manner. In this study, five couples experiencing marital difficulties participated in a traditional therapy group with emphasis upon cathartic release and problem solving. A similar group of five couples participated in a training group consisting of a systematic didactic and experiential approach emphasizing the ability to discriminate and communicate helpfully. The results of outcome measures assessing gain in interpersonal skills and overall functioning indicate significant improvement in the training as compared to the traditional group.