Central Limit Theorem approximations for the number of runs in Markov-dependent binary sequences

We consider Markov-dependent binary sequences and study various types of success runs (overlapping, non-overlapping, exact, etc.) by examining additive functionals based on state visits and transitions in an appropriate Markov chain. We establish a multivariate Central Limit Theorem for the number of these types of runs and obtain its covariance matrix by means of the recurrent potential matrix of the Markov chain. Explicit expressions for the covariance matrix are given in the Bernoulli and a simple Markov-dependent case by expressing the recurrent potential matrix in terms of the stationary distribution and the mean transition times in the chain. We also obtain a multivariate Central Limit Theorem for the joint number of non-overlapping runs of various sizes and give its covariance matrix in explicit form for Markov dependent trials.     

Efficiency determinants in retail stores: a Bayesian framework

This paper analyzes the impact of vertical integration, age, geographic expansion, and low price strategy on the cost efficiency of retail stores. We test our hypotheses using the innovative Bayesian frontier methodology. The data involve a sample of Spanish retail stores that operate in a highly competitive and dynamic environment. From the results, it is clear that cost efficiency is higher for stores that have: longer years in business, stronger geographical presence, and lower price offerings. Vertical integration, on the other hand, is negatively related to efficiency. Further discussions of these findings and related managerial implications are provided in the paper.     

Dose-Response Assessment of Airborne Methyl Isothiocyanate (MITC) Following a Metam Sodium Spill

A tank car derailment in northern California in 1991 spilled metam sodium into the Sacramento River, and released its breakdown product, methyl isothiocyanate (MITC), into the air. This paper describes the risk evaluation process used. Over 240 individuals reported symptoms such as eye and throat irritation, dizziness, and shortness of breath. Reference exposure levels (RELs) for 1 hr were developed for MITC and compared to exposure concentrations. Ocular irritation in cats was the most sensitive endpoint reported. The no observed adverse effect level (NOAEL), divided by an uncertainty factor (UF) of 100, produced an REL of 0.5 ppb of MITC in air to prevent discomfort. An REL to prevent disability was estimated to be 40 ppb. An REL to prevent life-threatening injury was estimated to be 150 ppb. Measured MITC levels ranged from 0.2-37 ppb and estimated peak levels ranged from 140-1600 ppb. The usefulness of RELs for emergency planning is discussed.     

Programmed Strategic Decision Making: The View From Mintzberg's Window1

A class of decisions, asset mix decisions made by pension fund managers, which exhibit characteristics of both programmed and strategic choices is examined in this paper. The decisions are classified using the scheme developed by Mintzberg et al., (1976) to highlight the circumstances under which strategic decisions may be programmed. The types of strategic decisions which lend themselves to programming are considered. The advantages and disadvantages of programming strategic decisions are also discussed.     

Wirth,Whiskey, and WASP's: Some Consequences of Community Size for Alcohol Use*†

Several themes in Wirth's “Urbanism as a Way of Life” generate the prediction that alcohol use (versus nonuse) will be more widespread among residents of urban areas. Multiple regression analysis of data from two recent national polls (1966, 1968) reveals support for this prediction. With eight other key sociological variables simultaneously controlled, the greater the urbanism of a community (measured in terms of community size), the greater the proportion of alcohol users it contains. To make certain that this association is due to urban conditions (as opposed to merely the absence of rural forces which encourage abstinence), the effects of rural forces are reduced by omitting the most rural categories of the community size measure of urbanism, and the data are reexamined. The association still persists, basically because of the larger proportion of middle to upper status, white, and Protestant alcohol users in the more urban areas.     

Exploring the prevalence and correlates of methamphetamine use: findings from Sacramento's ADAM program

Anecdotal reports have suggested that the use and abuse of methamphetamine is increasing in the United States. To date, however, few scholarly works have explored the prevalence and correlates of methamphetamine use in the United States. To address this limitation, a secondary analysis was undertaken with data collected through the Arrestee Drug Abuse Monitoring (ADAM) Program. An examination of methamphetamine-positive rates among ADAM arrestees interviewed between 1991 and 2001 identified that its use is concentrated within the Western part of the United States. Supplementary analyses of Sacramento arrestees indicated that 71% were diagnosed as needing some form of alcohol or other drug treatment. Compared to those arrestees who were detected methamphetamine-negative, methamphetamine-positive arrestees in Sacramento were three times as likely to be white and to have been diagnosed in need of drug treatment. Implications for drug control policy are discussed.