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81.
82.
In the development of many diseases there are often associated random variables which continuously reflect the progress of a subject towards the final expression of the disease (failure). At any given time these processes, which we call stochastic covariates, may provide information about the current hazard and the remaining time to failure. Likewise, in situations when the specific times of key prior events are not known, such as the time of onset of an occult tumour or the time of infection with HIV-1, it may be possible to identify a stochastic covariate which reveals, indirectly, when the event of interest occurred. The analysis of carcinogenicity trials which involve occult tumours is usually based on the time of death or sacrifice and an indicator of tumour presence for each animal in the experiment. However, the size of an occult tumour observed at the endpoint represents data concerning tumour development which may convey additional information concerning both the tumour incidence rate and the rate of death to which tumour-bearing animals are subject. We develop a stochastic model for tumour growth and suggest different ways in which the effect of this growth on the hazard of failure might be modelled. Using a combined model for tumour growth and additive competing risks of death, we show that if this tumour size information is used, assumptions concerning tumour lethality, the context of observation or multiple sacrifice times are no longer necessary in order to estimate the tumour incidence rate. Parametric estimation based on the method of maximum likelihood is outlined and is applied to simulated data from the combined model. The results of this limited study confirm that use of the stochastic covariate tumour size results in more precise estimation of the incidence rate for occult tumours. 相似文献
83.
D. R. Wingo 《Statistical Papers》1993,34(1):271-276
In a recent paper in this journal, Lee, Kapadia and Brock (1980) developed maximum likelihood (ML) methods for estimating the scale parameter of the Rayleigh distribution from doubly censored samples. They reported convergence difficulties in attempting to solve numerically the nonlinear likelihood equation (LE). To mitigate these difficulties, they employed approximations to simplify the LE, but found that the solution of the resulting simplified equation can give rise to parameter estimates of erratic accuracy. We show that the use of approximations to simplify the LE is unnecessary. In fact, under suitable parametric transformation, the log-likelihood function is strictly concave, the ML estimate always exists, is unique and finite. Furthermore, the LE is easy to solve numerically. A numerical example is given to illustrate the computations involved. 相似文献
84.
Rachel K. Jones 《Sociological inquiry》1993,63(3):351-361
Victims of spouse abuse were interviewed concerning their views of why their husbands were abusive. It was hypothesized that by concentrating on one specific characteristic of this kind previously undocumented patterns of response would be elicited from the subjects. It was concluded that the women's reasons for the violence perpetrated by their spouses serve as justification for the abusers’actions and legitimize maintenance of the relationship. 相似文献
85.
William A. Mueller D.M.D. 《Child and Adolescent Social Work Journal》1993,10(5):395-401
Dental caries in children is now recognized as a preventable disease. The use of fluoride and sealants has produced a major reduction in caries prevalence among school aged children in the United States and other countries. A portion of the child population who are educationally and socioeconomically disadvantaged are not fully receiving these benefits. Public policy, insurance and medicaid groups must be made aware of these preventative measures and strategies developed to implement them. 相似文献
86.
Using mail survey data based on a stratified systematic sample [N = 686] of 1983–1988 graduates of a medium-sized state university, this research evaluates whether ROTC program participation constitutes an independent source of human capital in civilian labor markets by comparing postgraduate earnings (annual income), prestige and authority, and life satisfaction of ROTC program participants with those of nonparticipants. The results revealed no statistically significant ROTC program participation effects, independent of subsequent military status. ROTC program participation paid off in terms of occupational prestige and authority for those on active duty, but not for those in national guard or reserve units. Neither ROTC participation nor current military status affected income or life satisfaction levels. 相似文献
87.
Neglected voices and excessive demands in feminist research 总被引:1,自引:1,他引:0
Shulamit Reinharz Ph.D. 《Qualitative sociology》1993,16(1):69-76
88.
89.
Dr. Judee K. Burgoon 《Journal of Nonverbal Behavior》1991,15(4):233-259
According to a social meaning model of nonverbal communication, many nonverbal behaviors have consensually recognized meanings. Two field experiments examined this presumption by investigating the relational message interpretations assigned to differing levels and types of touch, proximity, and posture. Also examined were the possible moderating effects of the communicator characteristics of gender and attractiveness and relationship characteristics of gender composition and status differentials. Results showed that touching typically conveyed more composure, immediacy, receptivity/trust, affection, similarity/depth/equality, dominance, and informality than its absence. The form of touch also mattered, with handholding and face touching expressing the most intimacy, composure, and informality; handholding and the handshake expressing the least dominance, and the handshake conveying the most formality but also receptivity/trust. Postural openness/relaxation paralleled touch in conveying greater intimacy, composure, informality, and similarity but was also less dominant than a closed/tense posture. Close proximity was also more immediate and similar but dominant. Proximity and postural openness together produced differential interpretations of composure, similarity, and affection. Gender initiator attractiveness was more influential than status in moderating interpretations.An earlier version of this paper was presented to the Interpersonal Communication Interest Group, Western States Communication Association convention, Phoenix, Arizona, February 1991. The author wishes to thank Leesa Dillman for her assistance on that version. 相似文献
90.
D. Eric Schansberg 《Economic inquiry》1994,32(3):445-456
Despite extensive study concerning involuntary departures by U.S. House members, little has been said about voluntary departures from the House–-quit behavior. This paper has three primary purposes: (1) to establish a theoretical framework that models the full range of choices a representative faces in any given term, (2) to measure the impact of different variables that affect representatives' quit behavior, and (3) to explain why Republicans have been more likely to pursue higher office than their Democratic colleagues. 相似文献