ISSN:0162-1459    

DOI:10.1080/01621459.1991.10474995

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT) measured the effectiveness of the drug cholestyramine for lowering cholesterol levels. The patients in the study were measured for compliance (the proportion of the intended dose actually taken) and for cholesterol decrease. The compliance-response regression for the Treatment group shows a smooth increasing effect of the drug in cholesterol level with increasing compliance. However, a similar, though less dramatic, compliance-response regression is seen in the Control group. This article investigates the recovery of the true dose-response curve from the Treatment and Control compliance-response curves. A simple model is proposed, analyzed, and applied to the LRC-CPPT data. Under this model, part but not all of the true dose-response curve can be estimated.

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10474996

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10474997

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10474998

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10474999

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10475000

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The fields of molecular genetics and medicine are accumulating DNA and protein sequence data at an accelerating rate. Discovering and interpreting sequence patterns can contribute to understanding molecular mechanisms and evolutionary processes. This article considers two types of statistical problems in these contexts: (1) identifying anomalies in the distribution of a specified biochemical marker along a DNA string; in particular, new statistical methods are set forth by which to assess excessive clustering, over dispersion, and too much regularity of the marker along the sequence. Applications are given to the physical map data of the bacteriumEscherichia coli. (2) Some results and statistical problems on the assembly of cloned DNA segments are also described. Sections 2 and 3 of the article present helpful background material on DNA organization and inheritance.

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10475001

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Patterns of Care Studies were conducted to determine the quality of care received by cancer patients whose primary treatment modality is radiation therapy. In this article, we propose and evaluate models which, if acceptable, permit Bayesian and frequentist model-based predictive inference for the desired finite population parameters. Using both hierarchical Bayesian and frequentist mixed linear models, we describe methodology for making the desired inferences, emphasizing the use of transformed random variables. Finally, we compare the frequentist, Bayes, and empirical Bayes approaches using data from one of the surveys. All three methods produce essentially the same value for the (finite population) mean. The standard empirical Bayes and frequentist measures of variability are very much smaller than those derived from the Bayesian approach, the latter reflecting uncertainty about the values of the scale parameters in the model.

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10475002

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Studies of regional climate following volcanic eruptions suggest that explosive volcanism exerts a short-term cooling effect. To understand the effects of explosive volcanism on historic temperatures, it is necessary to identify changes through time in the frequency of explosive eruptions. This article presents an exploratory analysis of a record of explosive eruptions in the Northern Hemisphere over the period 1851–1985. This record is modeled as a nonstationary Poisson process and the intensity function is estimated by kernel smoothing. Approximate confidence bands are constructed and diagnostics for checking the Poisson assumption are described. A comparison with a record of Northern Hemisphere temperatures indicates that part of the variability in temperature can be explained by variations in explosive volcanic activity.

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10475003

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A simple spatial-correlation model is presented for repeated measures data. Correlation between observations on the same subject is assumed to decay as a linear function of the squared distance separating the regions in three-dimensional space where the observations are made. This quadratic decay (QD) model has many attractive theoretical properties. The covariance structure of the “normalized” data, formed by subtracting the subject average, is the same as that generated by random linear trends plus centered white noise, which leads to a simple method for simulating the original data. It also implies that the first three principal components of the normalized observations are the spatial coordinates of the regions. Thus principal components analysis can be used as an exploratory tool to verify the QD model, provided the white noise component is small. Certain simple predictions can be made, such as the fact that the variances of the normalized observations increase linearly with the squared distance from the centroid of the regions, even though the original observations are assumed to have equal variance. This implies that it is harder to detect abnormal regional measurements in the outlying regions using normalized observations. Assuming multivariate normality, generalized least squares can be used to find maximum likelihood estimates of the QD model; calculations can be reduced using an expression for the inverse of the covariance matrix that only involves the inverse of a 3 × 3 matrix. It is shown, however, that although normalization simplifies the model by removing the random subject effect, it reduces information about the spatial correlation effect, making it harder to detect. This may have implications for other spatial-correlation models that are fitted to residuals from a sample mean. The QD model is applied to 30 cerebral regional glucose metabolism measurements from positron emission tomography (PET) images on a group of 20 normal subjects.

ISSN:0162-1459    

DOI:10.1080/01621459.1991.10475004

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor