Parental spanking and subsequent risk for child aggression in father-involved families of young children

This study examined separate and combined maternal and paternal use of spanking with children at age 3 and children's subsequent aggressive behavior at age 5. The sample was derived from a birth cohort study and included families (n = 923) in which both parents lived with the child at age 3. In this sample, 44% of 3-year-olds were spanked 2 times or more in the past month by either parent or both parents. In separate analyses, being spanked more than twice in the prior month at age 3, by either mother or father, was associated with increased child aggression at 5 years. In combined analyses, there was a dose–response association; the greatest risk for child aggression was reported when both parents spanked more than twice in the prior month (adjusted odds ratio: 2.01; [confidence interval: 1.03–3.94]). Violence prevention initiatives should target and engage mothers and fathers in anticipatory guidance efforts aimed at increasing the use of effective and non-aggressive child discipline techniques and reducing the use of spanking.     

Efficient ascertainment schemes for maximum likelihood estimation

While well chosen sampling schemes may substantially increase efficiency of observational studies, some sampling schemes may instead decrease efficiency. Rules of thumb how to choose sampling schemes are only available for some special cases. In this paper we provide tools to compare efficiencies, and cost adjusted efficiencies, of different sampling schemes, in order to facilitate this choice. The method can be used for both categorical and continuous outcome variables. Some examples are presented, focusing on data from ascertainment sampling schemes. A Monte Carlo method is used to overcome computational issues wherever needed. The results are illustrated in graphs.     

Spatiotemporal prediction for log-Gaussian Cox processes

Space–time point pattern data have become more widely available as a result of technological developments in areas such as geographic information systems. We describe a flexible class of space–time point processes. Our models are Cox processes whose stochastic intensity is a space–time Ornstein–Uhlenbeck process. We develop moment-based methods of parameter estimation, show how to predict the underlying intensity by using a Markov chain Monte Carlo approach and illustrate the performance of our methods on a synthetic data set.     

Performance characteristics of the adjusted r2 algorithm for determining the start of the terminal disposition phase and comparison with a simple r2 algorithm and a visual inspection method

The adjusted r² algorithm is a popular automated method for selecting the start time of the terminal disposition phase (t_z) when conducting a noncompartmental pharmacokinetic data analysis. Using simulated data, the performance of the algorithm was assessed in relation to the ratio of the slopes of the preterminal and terminal disposition phases, the point of intercept of the terminal disposition phase with the preterminal disposition phase, the length of the terminal disposition phase captured in the concentration‐time profile, the number of data points present in the terminal disposition phase, and the level of variability in concentration measurement. The adjusted r² algorithm was unable to identify t_z accurately when there were more than three data points present in a profile's terminal disposition phase. The terminal disposition phase rate constant (λ_z) calculated based on the value of t_z selected by the algorithm had a positive bias in all simulation data conditions. Tolerable levels of bias (median bias less than 5%) were achieved under conditions of low measurement variability. When measurement variability was high, tolerable levels of bias were attained only when the terminal phase time span was 4 multiples of t_1/2 or longer. A comparison of the performance of the adjusted r² algorithm, a simple r² algorithm, and t_z selection by visual inspection was conducted using a subset of the simulation data. In the comparison, the simple r² algorithm performed as well as the adjusted r² algorithm and the visual inspection method outperformed both algorithms. Recommendations concerning the use of the various t_z selection methods are presented.     

Optimal Method for Realizing Two-Sided Inferences About a Linear Combination of Two Proportions

In order to reach the inference about a linear combination of two independent binomial proportions, various procedures exist (Wald's classic method, the exact, approximate, or maximized score methods, and the Newcombe-Zou method). This article defines and evaluates 25 different methods of inference, and selects the ones with the best behavior. In general terms, the optimal method is the classic Wald method applied to the data to which z ² _α/2/4 successes and z ² _α/2/4 failures are added (≈1 if α = 5%) if no sample proportion has a value of 0 or 1 (otherwise the added increase may be different).

Supplemental materials are available for this article. Go to the publisher's online edition of Communications in Statistics - Simulation and Computation to view the free supplemental file.     

Adjusted Pearson residuals in beta regression models

In this paper, matrix formulae of order n^?1, where n is the sample size, for the first two moments of Pearson residuals are obtained in beta regression models. Adjusted Pearson residuals are also obtained, having, to this order, expected value zero and variance one. Monte Carlo simulation results are presented illustrating the behaviour of both adjusted and unadjusted residuals.     

Space-time Multi Type Log Gaussian Cox Processes with a View to Modelling Weeds

Log Gaussian Cox processes as introduced in Moller et al. (1998) are extended to space-time models called log Gaussian Cox birth processes. These processes allow modelling of spatial and temporal heterogeneity in time series of increasing point processes consisting of different types of points. The models are shown to be easy to analyse yet flexible enough for a detailed statistical analysis of a particular agricultural experiment concerning the development of two weed species on an organic barley field. Particularly, the aspects of estimation, model validation and intensity surface prediction are discussed.     

Diminishing Willingness to Pay per Quality‐Adjusted Life Year: Valuing Acute Foodborne Illness

We design and conduct a stated‐preference survey to estimate willingness to pay (WTP) to reduce foodborne risk of acute illness and to test whether WTP is proportional to the corresponding gain in expected quality‐adjusted life years (QALYs). If QALYs measure utility for health, then economic theory requires WTP to be nearly proportional to changes in both health quality and duration of illness and WTP could be estimated by multiplying the expected change in QALYs by an appropriate monetary value. WTP is elicited using double‐bounded, dichotomous‐choice questions in which respondents (randomly selected from the U.S. general adult population, n = 2,858) decide whether to purchase a more expensive food to reduce the risk of foodborne illness. Health risks vary by baseline probability of illness, reduction in probability, duration and severity of illness, and conditional probability of mortality. The expected gain in QALYs is calculated using respondent‐assessed decrements in health‐related quality of life if ill combined with the duration of illness and reduction in probability specified in the survey. We find sharply diminishing marginal WTP for severity and duration of illness prevented. Our results suggest that individuals do not have a constant rate of WTP per QALY, which implies that WTP cannot be accurately estimated by multiplying the change in QALYs by an appropriate monetary value.     

Integrated Approaches for the Public Health Prioritization of Foodborne and Zoonotic Pathogens

To address the persistent problems of foodborne and zoonotic disease, public health officials worldwide face difficult choices about how to best allocate limited resources and target interventions to reduce morbidity and mortality. Data‐driven approaches to informing these decisions have been developed in a number of countries. Integrated comparative frameworks generally share three methodological components: estimating incidence of acute illnesses, chronic sequelae, and mortality; attributing pathogen‐specific illnesses to foods; and calculating integrated measures of disease burden such as cost of illness, willingness to pay, and health‐adjusted life years (HALYs). To discuss the similarities and differences in these approaches, to seek consensus on principles, and to improve international collaboration, the E.U. MED‐VET‐NET and the U.S.‐based Food Safety Research Consortium organized an international conference convened in Berlin, Germany, on July 19–21, 2006. This article draws in part on the deliberations of the conference and discusses general principles, data needs, methodological issues and challenges, and future research needs pertinent to objective data‐driven analyses and their potential use for priority setting of foodborne and zoonotic pathogens in public health policy.     

Robust estimation of dropout models using hierarchical likelihood

It is very well known that analyses for missing data depend on untestable assumptions. As a consequence, in such settings, sensitivity analyses are often sensible. One such class of analyses assesses the dependence of conclusions on an explicit missing value mechanism. Inevitably, there is an association between such dependence and the actual (but unknown) distribution of the missing data. In a particular parametric framework for dropout in this paper, an approach is presented that reduces (but never removes) the impact of incorrect assumptions on the form of the association. It is shown how these models can be formulated and fitted relatively simply using hierarchical likelihood. These are applied directly to an example involving mastitis in dairy cattle, and an extensive simulation study is described to show the properties of the methods.