An EM type estimation procedure for the destructive exponentially weighted Poisson regression cure model under generalized gamma lifetime

In this paper, we assume the number of competing causes to follow an exponentially weighted Poisson distribution. By assuming the initial number of competing causes can undergo destruction and that the population of interest has a cure fraction, we develop the EM algorithm for the determination of the MLEs of the model parameters of such a general cure model. This model is more flexible than the promotion time cure model and also provides an interesting and realistic interpretation of the biological mechanism of the occurrence of an event of interest. Instead of assuming a particular parametric distribution for the lifetime, we assume the lifetime to belong to the wider class of generalized gamma distribution. This allows us to carry out a model discrimination to select a parsimonious lifetime distribution that provides the best fit to the data. Within the EM framework, a two-way profile likelihood approach is proposed to estimate the shape parameters. An extensive Monte Carlo simulation study is carried out to demonstrate the performance of the proposed estimation method. Model discrimination is carried out by means of the likelihood ratio test and information-based methods. Finally, a data on melanoma is analyzed for illustrative purpose.     

Modeling of paired zero-inflated continuous data without breaking down paired designs

Paired data have been widely collected in the efficiency studies of a new method against an established method in environmental, ecological and medical studies. For example, in comparative fishing studies, ability of catching target species (fish catch) or reducing the catch of non-target species (fish bycatch) is usually investigated through a paired design. These paired fish catches by weight are generally skewed and continuous, but with a significant portion of exact zeros (no catch). Such zero-inflated continuous data are traditionally handled by two-part models where the zero and positive components are handled separately; however, this separation generally destroys paired structure, and thus may result in substantial difficulty in characterizing the relative efficiency between two methods. To overcome this problem, we consider compound Poisson mixed model for paired data with which the zero and non-zero components are characterized in an integral way. In our approach, the clustering effects by pair are captured by incorporating relevant random effects. Our model is estimated using orthodox best linear unbiased predictor approach. Unlike two-part models, our approach unifies inferences of zero and positive components. Our method is illustrated with analyses of winter flounder bycatch data and ultrasound safety data.     

Likelihood ratio test-based chart for monitoring the process variability

This article proposes a new chart with the generalized likelihood ratio (GLR) test statistics for monitoring the process variance of a normally distributed process. The new chart can be easily designed and constructed and the computation results show that it provides quite a satisfactory performance, including the detection of the decrease in the variance and the individual observation at the sampling point which are very important in many practical applications. Average run length (ARL) comparisons between other procedures and the new chart are presented. The optimal parameters that can be used as a design aid in selecting specific parameter values based on the ARL are described. The application of our proposed method is illustrated by a real data example from chemical process control.     

New confidence interval estimator of the signal-to-noise ratio based on asymptotic sampling distribution

In this paper, the asymptotic distribution of the signal-to-noise ratio (SNR) is derived and a new confidence interval for the SNR is introduced. An evaluation of the performance of the new interval compared to Sharma and Krishna (S–K) (1994) confidence interval for the SNR using Monte Carlo simulations is conducted. Data were randomly generated from normal, log-normal, χ², Gamma, and Weibull distributions. Simulations revealed that the performance of S–K interval is totally dependent on the amount of noise introduced and that it has a constant width for a given sample size. The S–K interval performs poorly in four of the distributions unless the SNR is around one. It is recommended against using the S–K interval for data from log-normal distribution even with SNR = 1. Unlike the S–K interval which does not account for skewness and kurtosis of the distribution, the new confidence interval for the SNR outperforms S–K for all five distributions discussed, especially when SNR?? 2. The proposed ranked set sampling (RSS) instead of simple random sampling (SRS) has improved the performance of both intervals as measured by coverage probability.     

On a new positive dependence concept based on the conditional mean inactivity time order

In this paper, we introduce a new positive dependence concept between two non negative random variables which is related to a conditional version of the mean inactivity time order. A number of properties and relationship between the new notion and the concept of positive likelihood ratio dependence (PLRD) is discussed. Some results in terms of proposed notions for the Archimedean family of copulas are provided.     

On hypothesis tests for disk-type intensities of spatial poisson processes

We consider the problem of testing whether realizations of a spatial Poisson process come from a circular intensity model or from an elliptical intensity model. We describe the behavior of the Generalized Likelihood Ratio and Wald tests, in the asymptotics of large samples. The power functions are studied under local alternatives and results of numerical simulations comparing them to the Neyman–Pearson envelope are presented.     

Some tests for the allometric extension model in regression

The allometric extension model is a multivariate regression model recently proposed by Tarpey and Ivey (2006 Tarpey, T., Ivey, C.T. (2006). Allometric extension for multivariate regression. J. Data Sci. 4:479–495. [Google Scholar]). This model holds when the matrix of covariances between the variables in the response vector y and the variables in the vector of regressors x has a particular structure. In this paper, we consider tests of hypotheses for this structure when (y′, x′)′ has a multivariate normal distribution. In particular, we investigate the likelihood ratio test and a Wald test.     

Does Mate Scarcity Affect Marital Choice and Family Formation? The Evidence for New and Classic Formulations of Sex Ratio Theory

Guttentag and Secord pioneered research on the social consequences of imbalances in the numbers of men and women—the sex ratio. Since then, sociologists, psychologists, anthropologists, and even biologists have investigated its effects on marriage and reproduction. I review the three prevailing theories to explain why sex ratio should affect marriage and reproduction, along with the evidence that it does. I also review the growing evidence that sex ratio imbalances are associated with mate choice. Sex ratio reveals contradictory relationships with mate preferences and actual partner choice, however, raising a conundrum for future research. Overall, there is strong experimental and correlational support for the patterns of marriage and reproduction associated with sex ratio. What emerges is the necessity for future research to distinguish among the perspectives to explain why.     

Exploring the implications of different loan-to-value macroprudential policy designs

We evaluate the macroeconomic effects of changes in loan-to-value ratios in a multi-country model with financial frictions and a banking sector. Main findings suggest that a permanent LTV tightening in a small euro area economy leads to a long-run decline in lending to the private sector. The short-run impact depends crucially on the policy design, being less pronounced when the measure is phased-in. This is consistent with policy goals of curbing credit growth but avoiding an abrupt immediate contraction. A euro area wide measure implies larger long-run effects but the short-run recessionary impact is attenuated by the monetary policy response.     

三态英语教学法重要指标的统计分析--三态英语系统教学理论及其教学法之五

本文通过对教学统计数据的分析和总结,说明三态英语系统教学理论及其教学法的合理性和必要性,以及在当今大学英语教学中所具有的综合性教学运用价值.