Fitting Markov chain models to discrete state series such as DNA sequences

Discrete state series such as DNA sequences can often be modelled by Markov chains. The analysis of such series is discussed in the context of log-linear models. The data produce contingency tables with similar margins due to the dependence of the observations. However, despite the unusual structure of the tables, the analysis is equivalent to that for data from multinomial sampling. The reason why the standard number of degrees of freedom is correct is explained by using theoretical arguments and the asymptotic distribution of the deviance is verified empirically. Problems involved with fitting high order Markov chain models, such as reduced power and computational expense, are also discussed.     

Convergence of Slice Sampler Markov Chains

We analyse theoretical properties of the slice sampler. We find that the algorithm has extremely robust geometric ergodicity properties. For the case of just one auxiliary variable, we demonstrate that the algorithm is stochastically monotone, and we deduce analytic bounds on the total variation distance from stationarity of the method by using Foster–Lyapunov drift condition methodology.     

Exiting shelter: an epidemiological analysis of barriers and facilitators for families

This study examines the role of individual- and family-level factors in predicting the length of shelter stays for homeless families. Interviews were conducted with all families exiting one of six emergency family shelters in Worcester, Massachusetts, between November 2006, and November 2007. Analyses, using an ordinary least squares regression model, find that families with a positive alcohol or drug screen in the year prior stay 85 days longer than those without a positive screen; families leaving shelter with a housing subsidy stay 66 days longer than those leaving without a subsidy. Demographic factors, education, employment, health, and mental health are not found to predict shelter stay duration. Consistent with prior research, housing resources relate to families' time in shelter; with the exception of a positive substance abuse screen, individual-level problems are not related to their time in shelter. Efforts to expand these resources at the local, state, and national levels are a high priority.     

Understanding Gender and Power Dynamics Within the Family: A Qualitative Study of Nepali Women's Experience

Among the Maori of New Zealand, Aboriginals of Australia, and other Indigenous peoples, family dynamics strongly influence the ways that issues emerge in counseling. This study explores aspects of gender and power within the context of birth practices in rural Nepal. In‐depth interviews were conducted with 15 postpartum women, as well as family members, to collect narratives of birthing experiences that highlight issues of oppression, marginalisation, and power struggles. Implications for multicultural and social justice awareness in family therapy are discussed, especially with regard to the subtle, disguised ways that power operates behind the scenes, often sabotaging efforts by health and mental health professionals to bemost helpful.     

Carbon fluxes and nitrogen availability along an urban–rural gradient in a desert landscape

Urbanization is increasing in arid and semi-arid regions of the world and impacting native ecosystems through disturbance, climatic modification, and pollution deposition. Arid ecosystems often exhibit a mosaic of shrub/tree canopy covered and non-canopy covered patches that differ in elemental pools and processes. We measured belowground ecosystem attributes and processes in native Larrea tridentata {(D.C.) Cov} dominated communities along an urban–rural gradient in Phoenix, Arizona. Organic carbon (C), total nitrogen (N), and nitrate levels were significantly greater in the urban locations, but soil respiration rates (R_s) were higher at the rural sites. Urban sites exhibited no difference in R_s and N between the canopy and interplant patches while both the rural and suburban sites had significantly greater N and higher R_s under the canopy than in the interplant spaces. Soil respiration rates at the urban locations were not correlated with either soil moisture or temperature individually. These data suggest that urbanization has caused a disconnect of ecological pattern and processes in L. tridentata ecosystems within the urban setting such that water and N limitations no longer explain expected spatial R_s patterns, or elemental pools.     

Anger and Approach Motivation in Infancy: Relations to Early Childhood Inhibitory Control and Behavior Problems

The relations among infant anger reactivity, approach behavior, and frontal electroencephalogram (EEG) asymmetry, and their relations to inhibitory control and behavior problems in early childhood were examined within the context of a longitudinal study of temperament. Two hundred nine infants’ anger expressions to arm restraint were observed at 4 months of age. Infants’ approach behaviors during play with an unpredictable toy and baseline frontal EEG asymmetry were assessed at 9 months of age. Inhibitory control during a Go/No‐Go task and parent report of behavior problems were evaluated at 4 years of age. High anger‐prone infants with left, but not right, frontal EEG asymmetry showed significantly more approach behaviors and less inhibitory control relative to less anger‐prone infants. Although a link between anger proneness in infancy and behavior problems in early childhood was not found, a combination of low approach behaviors and poor inhibitory control was predictive of internalizing behaviors.     

An Empirical Investigation of Costs in Batching Decisions*

This paper examines the use of costs and cost functions to model lot‐sizing decisions in batch manufacturing. The cost functions used to model a wide variety of manufacturing systems are typically derived from average cost models of unconstrained inventory problems. The use of setups and average inventories as the basis for modeling the economics of a typical batch manufacturing cell is shown to be inadequate. An alternative physical model that focuses on lead times provides a model that more closely represents the underlying value of such a cell.     

Density Estimation in Several Populations With Uncertain Population Membership

We devise methods to estimate probability density functions of several populations using observations with uncertain population membership, meaning from which population an observation comes is unknown. The probability of an observation being sampled from any given population can be calculated. We develop general estimation procedures and bandwidth selection methods for our setting. We establish large-sample properties and study finite-sample performance using simulation studies. We illustrate our methods with data from a nutrition study.     

Statistical considerations associated with a comprehensive regulatory framework to address the unmet need for new antibacterial therapies

At present, there are situations in antibiotic drug development where the low number of enrollable patients with key problem pathogens makes it impossible to conduct fully powered non‐inferiority trials in the traditional way. Recent regulatory changes have begun to address this situation. In parallel, statistical issues regarding the application of alternative techniques, balancing the unmet need with the level of certainty in the approval process, and the use of additional sources of data are critical areas to increase development feasibility. Although such approaches increase uncertainty compared with a traditional development program, this will be necessary to allow new agents to be made available. Identification of these risks and explicit discussion around requirements in these areas should help clarify the situation, and hence, the feasibility of developing drugs to treat the most concerning pathogens before the unmet need becomes even more acute than at present. Copyright © 2014 John Wiley & Sons, Ltd.     

A grounded theory research approach to building and testing TQM theory in operations management

Total quality management (TQM) has continued to develop as a strategic business improvement approach in organisations and within the Operations Management literature. Strategic TQM is a dynamic phenomenon, reflecting the complexity and technology development in the business environment. Therefore, this conception of TQM has led to significant challenges with regards to developing suitable models and research methodology where traditional, and normative research data, includes survey responses associated with deductive theory and testing. Such data, and its use, is often premised on cause and effect rationality and fails to supply deep rich data to address meanings, phenomena and complex socio-political events, which is a feature of strategic TQM.