A new long-term survival model with dispersion induced by discrete frailty

Lifetime Data Analysis - Frailty models are generally used to model heterogeneity between the individuals. The distribution of the frailty variable is often assumed to be continuous. However, there...     

Measures of Social Isolation

Social isolation is a deprivation of social connectedness. It is a crucial aspect that continues to be named by people as a core impediment for achieving well-being and as a relevant factor for understanding poverty. However it is not routinely included in surveys that provide data on multidimensional poverty measurement. Although the challenge of measuring social connectedness is daunting, this paper argues that existing research in several fields provides solid ground for the construction of basic internationally comparable indicators that measure specific aspects of social isolation. In particular, this paper synthesises the relevant literature on the measurement of social isolation and related phenomena, and on the basis of this synthetic review, proposes a module of indicators to measure social connectedness that could be feasibly incorporated into an internationally comparable multi-topic household survey.     

Likelihood-based tests in zero-inflated power series models

We address the issue of performing testing inference in the class of zero-inflated power series models. These models provide a straightforward way of modelling count data and have been widely used in practical situations. The likelihood ratio, Wald and score statistics provide the basis for testing the parameter of inflation of zeros in this class of models. In this paper, in addition to the well-known test statistics, we also consider the recently proposed gradient statistic. We conduct Monte Carlo simulation experiments to evaluate the finite-sample performance of these tests for testing the parameter of inflation of zeros. The numerical results show that the new gradient test we propose is more reliable in finite samples than the usual likelihood ratio, Wald and score tests. An empirical application to real data is considered for illustrative purposes.