background: effect of seasonal changes in human reproduction has been intensively researched. some studies acknowledge influences of seasonal variation on natural conception, while others can not confirm them. the aim of this study was to investigate the effect of seasonal changes on different stages of assisted reproductive technology (art) in tehran. materials and methods: this study was carr...

In this paper, a four parameters extension of the generalized Lindley distribution is introduced. The new distribution includes the power Lindley, Lindley, generalized (Stacy) gamma, gamma, Weibull, Rayleigh, exponential and half-normal distribution. Several statistical properties of the distribution are explored. Then, a bivariate version of the proposed distribution is derived. Using a simula...

Abstract In this paper, we introduce a new distribution on Z, which can be viewed as a natural bivariate extension of the Skellam distribution. The main feature of this distribution a possible dependence of the univariate components, both following univariate Skellam distributions. We explore various properties of the distribution and investigate the estimation of the unknown parameters via the...

Discrete-valued time series modeling has witnessed numerous bivariate first-order integer-valued autoregressive process or BINAR(1) processes based on binomial thinning and different innovation distributions. These are mainly focused over-dispersion. This paper aims to propose new distributions a recently proposed over-dispersed distribution: the Poisson 2S-Lindley distribution. The distributio...

The Gompertz distribution has many applications, particularly in medical and actuarial studies. However, there has been little recent work on the Gompertz in comparison with its early investigation. The problem of analyzing and estimating parameters of bivariate Gompertz distribution with shared frailty is of interest and the focus of this paper. We propose maximum likelihood estimation procedu...

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is an economically important pest of ornamental plant in Iran. The population abundance and spatial distribution were studied on five Rosa cultivars including Maroussia, Wendela, Elderado, Wenedetta, and Hot Lady during two growing seasons of 2011 and 2012 in greenhouse. The k parameter, index of dispersion, Lloyd’s m...

Univariate Birnbaum-Saunders distribution has received a considerable amount of attention in recent years. Rieck and Nedelman (1991, ’A log-linear model for the Birnbaum-Saunders distribution’, Technometrics, 51-60) introduced a log BirnbaumSaunders distribution. The main aim of this paper is to introduce bivariate log Birnbaum-Saunders distribution. The proposed model is symmetric and it has f...

Marshall and Olkin (1997) provided a general method to introduce a parameter into a family of distributions, and discussed in details about the exponential and Weibull families. They have also briefly introduced the bivariate extension, although not any properties or inferential issues have been explored, mainly due to analytical intractability of the general model. In this paper we consider th...