Maximum likelihood estimation of variance components in a completely random bib design

ABSTRACT

The purposes of this paper are to abstract from a number of articles variance component estimation procedures which can be used for completely random balanced incomplete block designs, to develop an iterated least squares (ITLS) computing algorithm for calculating maximum likelihood estimates, and to compare these procedures by use of simulated experiments. Based on the simulated experiments, the estimated mean square errors of the ITLS estimates are generally less than*those for previously proposed analysis of variance and symmetric sums estimators.     

Statistical techniques in stereology

Stereology typically concerns estimation of properties of a geometric structure from plane section information. This paperprovides a brief review of some statistical aspects of this rapidly developing field, with some reference to applications in the earth sciences. After an introductory discussion of the scope of stereology, section 2 briefly mentions results applicable when no assumptions can be made about the stochastic nature of the sampled matrix, statistical considerations then arising solelyfrom the ‘randomness’ of the plane section. The next two sections postulate embedded particles of specific shapes, the particular case of spheres being discussed in some detail.

References are made to results for ‘thin slices’ and other prob-ing mechanisms. Randomly located convex particles, of otherwise arbitrary shape, are discussed in section 5 and the review concludes with a specific application of stereological ideas to some data on neolithic mining.     

Editorial

Drawing on texts written by young people aged 14–17 years in a school context in response to an invitation to write a page describing themselves and their vision of Ireland and to use the reverse side creatively for drawings, poems or songs, this article illustrates the methodological difficulties of exploring globalization and individualization in such texts. The indicators of globalization were global entertainment and consumer culture, global technology, references to international travel, and global concerns. The indicators of individualization were the absence of references to structural location, or the presence of references to choices, hopes or plans and related images. There were insurmountable methodological difficulties in differentiating between individualization in these terms and stereotypical ways of ‘doing boy/girl’. Hence, the typology that was created focussed on the global content of the main texts and back pages and their gendered content.     

Failure Probability Under Parameter Uncertainty

In many problems of risk analysis, failure is equivalent to the event of a random risk factor exceeding a given threshold. Failure probabilities can be controlled if a decisionmaker is able to set the threshold at an appropriate level. This abstract situation applies, for example, to environmental risks with infrastructure controls; to supply chain risks with inventory controls; and to insurance solvency risks with capital controls. However, uncertainty around the distribution of the risk factor implies that parameter error will be present and the measures taken to control failure probabilities may not be effective. We show that parameter uncertainty increases the probability (understood as expected frequency) of failures. For a large class of loss distributions, arising from increasing transformations of location‐scale families (including the log‐normal, Weibull, and Pareto distributions), the article shows that failure probabilities can be exactly calculated, as they are independent of the true (but unknown) parameters. Hence it is possible to obtain an explicit measure of the effect of parameter uncertainty on failure probability. Failure probability can be controlled in two different ways: (1) by reducing the nominal required failure probability, depending on the size of the available data set, and (2) by modifying of the distribution itself that is used to calculate the risk control. Approach (1) corresponds to a frequentist/regulatory view of probability, while approach (2) is consistent with a Bayesian/personalistic view. We furthermore show that the two approaches are consistent in achieving the required failure probability. Finally, we briefly discuss the effects of data pooling and its systemic risk implications.     

Austin Turk,stratification reinforcers and reversals,and traffic ticket decisions by Boston police during April and May of 2001

Austin Turk theorizes that places in stratification hierarchies affect police–citizen encounters by reinforcing or reversing the positional authority of police officers. To this point, however, there have been only three direct tests of the stratification portions of Turk's theory. Two examined overt conflict and all represented Turk's concepts using aggregated measures. The results are mixed. The present research adds a fourth test to the stratification and policing literatures by examining the effects of aggregated as well as disaggregated measures of stratification reinforcers and reversals on traffic ticket decisions by Boston police officers during April and May of 2001. Net of important control measures, there is no support for Turk's theory using the aggregated stratification measures employed in previous research. However, support for Turk's theory is clearly visible when viewed through the lens of some of the disaggregated stratification measures advanced for the first time in present research. We conclude that more research is needed to determine whether stratification reinforcers and reversals are among the factors affecting people in police blue and the people they police, with a sustained focus on both aggregated and disaggregated measures.     

Multiple Co-occurring Behaviours among Gamblers in Treatment: Implications and Assessment

A substantial portion of gamblers in treatment may have co-occurring mental health disorders including substance use disorders, especially alcohol dependency, personality disorders, affective disorders, anxiety disorders and impulse control disorders. Co-occurring mental health disorders affect treatment seeking, the treatment process and its outcome, quality of life and functioning in many mental health disorders. Participants in this study were 78 adults enrolled in state-supported out-patient services for pathological gambling and current Gamblers Anonymous attendees. The majority of participants (76.6%) had co-occurring behaviours; 55.8% had multiple co-occurring behaviours. Participants with multiple co-occurring behaviours were more likely to report that a co-occurring behaviour increased the severity of their gambling symptoms. A dose/response relationship between number of co-occurring behaviours and severity of gambling problems was found. Co-occurring behaviours can interact with gambling behaviour. Brief, validated screening instruments are available for screening and diagnosing co-occurring behaviours among gamblers presenting for treatment.     

Slope Estimation for Bivariate Longitudinal Outcomes Adjusting for Informative Right Censoring Using Discrete Survival Model: Application to the Renal Transplant Cohort

Patients undergoing renal transplantation are prone to graft failure which causes lost of follow-up measures on their blood urea nitrogen and serum creatinine levels. These two outcomes are measured repeatedly over time to assess renal function following transplantation. Loss of follow-up on these bivariate measures results in informative right censoring, a common problem in longitudinal data that should be adjusted for so that valid estimates are obtained. In this study, we propose a bivariate model that jointly models these two longitudinal correlated outcomes and generates population and individual slopes adjusting for informative right censoring using a discrete survival approach. The proposed approach is applied to the clinical dataset of patients who had undergone renal transplantation. A simulation study validates the effectiveness of the approach.