The authors describe a method for fitting failure time mixture models that postulate the existence of both susceptibles and long-term survivors when covariate data are only partially observed. Their method is based on a joint model that combines a Weibull regression model for the susceptibles, a logistic regression model for the probability of being a susceptible, and a general location model f...

Data analysis is a quite important process and has been extensively employed in many areas. Especially in statistics, the distribution type test of data often needs to be handled. This paper presents that linear regression as a type of universal method can be applied to the distribution type test. In reliability engineering due to the failure data is commonly of non-linear relationship so that ...

The Weibull function is frequently chosen to define psychometric functions. Tyler and Chen (Vis. Res. 40 (2000) 3121) criticised the high-threshold postulate implied by the Weibull function and argued that this function implies the assumption of multiplicative noise. It will be shown in this paper that in fact the Weibull function is compatible with the assumption of additive noise, and that th...

Motivated by the recent popularization of beta prime distribution, a more flexible generalization is presented to fit symmetrical or asymmetrical and bimodal data, non-monotonic failure rate. Thus, Weibull-beta distribution defined, some its structural properties are obtained. The parameters estimated maximum likelihood, new regression model proposed. Some simulations reveal that estimators con...

A three-parameter Weibull distribution model was developed and verified to simulate the underlying frequency distributions of observations with missing values through the entire range of observations or near and below detection limit of the monitoring equipment. The corresponding Weibull pseudo-random generator then can be used to estimate and replace the missing observations so that the origin...

A new stochastic fading channel model called cascaded Weibull fading is introduced and the associated capacity is derived in closed form. This model is generated by the product of independent, but not necessarily identically distributed, Weibull random variables (RVs). By quantifying the convergence rate of the central limit theorem as pertaining to the multiplication of Weibull distributed RVs...

the hydrothermal time models have been widely applied to describe the germination responses of seeds to temperature and water potential. in this study, three hydrothermal time models developed on the basis of different statistical distributions (normal, weibull and gumbel) were compared to describe the phalaris minor seed germination. results showed that gumbel (aicc=-762.8) and weibull (aicc=-...

Wind speed is the most important parameter in the design and study of the environmental impact assessment. The wind speed determines the concentration of any toxic pollutant released from any chemical industry. As the wind speed increases the concentration of the toxic pollutant at any location in the environment at any instant of time decreases. It is also known that as the wind speed increase...

BACKGROUND Researchers in the medical sciences prefer employing Cox model for survival analysis. In some cases, however, parametric methods can provide more accurate estimates. In this study, we used Weibull model to analyze the prognostic factors in patients with gastric cancer and compared with Cox. METHODS We retrospectively studied 1715 patients with gastric cancer. Age at diagnosis, gend...