Preface xiüChapter 1 Introduction: The Bayesian Method, its Beneflts and Implementation 1.1The Bayes approach and its potential advantages 1.2Expressing prior uncertainty about parameters and Bayesian updating 1.3 MCMC sampling and inferences from posterior densities 1.4The main MCMC sampling algorithms 1.4.1 Gibbs sampling 1.5Convergenceof MCMCsamples 1.6Predictions from sampling: using the posterior predictive density 1.7The present book References Chapter 2 Bayesian Model Choice, Comparison and Checking

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Sum m ary. T his study discu sses variab ility in the spatial prevalen ce of suicid e and parasu icid e across sm all areas in London in relation to the social and dem ograph ic com position of their population s. The focu s is on the relative im portan ce in exp lain ing suicid al outcom es of variab les represen ting resp ectively social deprivation , psych iatric m orb idity and anom ie (or com m unity fragm entation ), and of differen tiation in the effects of these factors across sub-population s. There is stron g evid ence for such con textu al effectsÐ nam ely, varyin g effects of these socio-ec onom ic factors accord ing to geograp hical settin gÐ as w ell as for differen tial associa tion s by age grou p, sex and type of outcom e (suicid e vs parasu icid e).

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This article describes the development and validation of a test of vocabulary size and strength. The ® rst part of the article sets out the theoretical rationale for the test, and describes how the size and strength constructs have been conceptualized and operationalized. The second part of the article focusses on the process of test validation, which involved the testing of the hypotheses implicit in the test design, using both unidimensional and multifaceted Rasch analyses. Possible applications for the test include determining the status of a learner's vocabulary development as well as screening and placement. A model for administering the test in computer adaptive mode is also proposed. The study has implications both for the design and delivery of this test as well as for theories of vocabulary acquisition.

Study objective -To assess the nature of the relation between health and social factors at both the aggregated scale of geographical areas and the individual scale. Design and setting -The individual data are derived from the sample of anonymised records (SAR) from the census of 1991 in Great Britain, and are combined' with area data from this census. The ecological setting (context) was defined using multivariate methods to classify the 278 districts of residence identifiable in the SAR. The outcome health variable is the 1991 census long-term limiting illness question. Health variations were analysed by multilevel logistic regression to examine the compositional variation (at the level of the individual) and the contextual variation (variability operating at the level of districts) in reported illness. Participants -10 per cent randomised subsample of the SAR who are aged 16 + and are resident in households. Main results -The multi-level modelling revealed that area factors have a significant association with individual health outcome but their effect is smaller than that of individual attributes. The results show evidence for both compositional and contextual effects in the pattern of variation in propensity to report illness. Conclusions -The results suggest generally higher levels of ill health for individuals who are older, not married, in a semi/unskilled manual social class, and socioeconomically deprived (as measured by a composite deprivation score). All individuals living in areas with high levels of illness (which tend to be more deprived areas) show greater morbidity, even after allowing for their individual characteristics. However, within affluent areas, where morbidity was generally lower, the health inequality (health gradient) between rich and poor individuals was particularly strong. We consider the implications of these findings for health and resource allocation policy.(JT Epidemiol Community Health 1996;50:366-376) This paper examines some aspects of health inequalities and their associations with socioeconomic conditions in the British population. While most measures of population health demonstrate inequalities in health status, the patterns observed depend on the type of indicator used and the aspect of health it measures.The measure of health considered here comes from the 1991 census question on longterm limiting illness, which is a self assessed measure of health status. It may be more affected by subjectivity and imprecision than other health measures such as mortality and physiological measures. However, premature mortality can be the result of chronic ill health, and perceived health status is a good predictor of mortality.' Moreover, chronic illness encompasses disabling conditions not usually associated with mortality, and provides a more comprehensive health status measure. Self reported health is also associated with physiological health2 and general practitioner and hospital utilisation.3 The 1991 census measure has been shown to be ecologically associated with mort...

The purpose of this study was to investigate the stability of rater severity over an extended rating period. Multifaceted Rasch analysis was applied to ratings of 16 raters on writing performances of 8, 285 elementary school students. Each performance was rated by two trained raters over a period of seven rating days. Performances rated on the first day were re‐rated at the end of the rating period. Statistically significant differences between raters were found within each day and in all days combined. Daily estimates of the relative severity of individual raters were found to differ significantly from single, on‐average estimates for the whole rating period. For 10 raters, severity estimates on the last day were significantly different from estimates on the first day. These fndings cast doubt on the practice of using a single calibration of rater severity as the basis for adjustment of person measures.

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