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71.
We consider the competing risks set-up. In many practical situations, the conditional probability of the cause of failure given the failure time is of direct interest. We propose to model the competing risks by the overall hazard rate and the conditional probabilities rather than the cause-specific hazards. We adopt a Bayesian smoothing approach for both quantities of interest. Illustrations are given at the end.  相似文献   
72.
Given spatially located observed random variables ( x , z = {( x i , z i )} i , we propose a new method for non-parametric estimation of the potential functions of a Markov random field p ( x | z ), based on a roughness penalty approach. The new estimator maximizes the penalized log-pseudolikelihood function and is a natural cubic spline. The calculations involved do not rely on Monte Carlo simulation. We suggest the use of B-splines to stabilize the numerical procedure. An application in Bayesian image reconstruction is described.  相似文献   
73.
Theory Trimming     
This paper attempts to show that the “Theory Trimming” technique makes little contribution to theory in sociology. A brief history of the technique is given, and several key assertions of its proponents are abstracted. These assertions are shown to be highly questionable. The general alternative to Theory Trimming is shown, and the relationship between Theory Trimming and more general orientations to research is discussed.  相似文献   
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Units of observation such as census tracts continue to be analyzed according to various modal characteristics while the variation or diversity existent in such units is often ignored. The qualitative or nominal-level indicators of diversity are examined which (1) are operative in the polytomous situation, and (2) measure within-unit diversity rather than divergences among units. Six qualitative indicators are explained and compared both theoretically and by example, with the Index of Qualitative Variation suggested as the most appropriate measure of diversity when variables representing a nominal scale are used. Quantitative or interval-level diversity also was examined with six measures analyzed, representing three operational situations. Because of the susceptibilities of five of the quantitative measures to skewness and variable sample sizes, the coefficient of variation was recommended for interval-level variables to evaluate within-unit diversity.  相似文献   
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Summary An equation is given for the estimation of selective values from data obtained by mark-recapture experiments, assuming that selective pressures remain constant while the experiments are carried out. The equation does not have an explicit solution but can readily be solved using a trial-and-error method. The use of the equation is illustrated on some data reported byKettlewell et al. (1969) from an experiment involvingtypica andedda morphs of the mothAmathes glareosa. It is found that theedda morph apparently had a selective advantage of about 12% per day compared to thetypica morph and that this is significantly different from zero. Using another methodKettlewell concluded that the selective advantage of theedda morph was only 7% and that this was not statistically significant.  相似文献   
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