A rich learning lesson using the Poisson distribution

In this note, we explore the rich information about inference that the Poisson distribution has. The source of this information is mainly the fact that the mean and variance of this distribution are equal.     

Multilevel zero-inflated negative binomial regression modeling for over-dispersed count data with extra zeros

Count data with excess zeros often occurs in areas such as public health, epidemiology, psychology, sociology, engineering, and agriculture. Zero-inflated Poisson (ZIP) regression and zero-inflated negative binomial (ZINB) regression are useful for modeling such data, but because of hierarchical study design or the data collection procedure, zero-inflation and correlation may occur simultaneously. To overcome these challenges ZIP or ZINB may still be used. In this paper, multilevel ZINB regression is used to overcome these problems. The method of parameter estimation is an expectation-maximization algorithm in conjunction with the penalized likelihood and restricted maximum likelihood estimates for variance components. Alternative modeling strategies, namely the ZIP distribution are also considered. An application of the proposed model is shown on decayed, missing, and filled teeth of children aged 12 years old.     

A 6.55 factor primal-dual approximation algorithm for the connected facility location problem

In the connected facility location (ConFL) problem, we are given a graph G=(V,E) with nonnegative edge cost c _e on the edges, a set of facilities ??V, a set of demands (i.e., clients) $\mathcal{D}\subseteq VIn the connected facility location (ConFL) problem, we are given a graph G=(V,E) with nonnegative edge cost c _e on the edges, a set of facilities ℱ⊆V, a set of demands (i.e., clients) D í V\mathcal{D}\subseteq V , and a parameter M≥1. Each facility i has a nonnegative opening cost f _i and each client j has d _j units of demand. Our objective is to open some facilities, say F⊆ℱ, assign each demand j to some open facility i(j)∈F and connect all open facilities using a Steiner tree T such that the total cost, which is ?_{i ? F}f_i+?_{j ? D}d_jc_i(j)j+M?_{e ? T}c_e\sum_{i\in F}f_{i}+\sum_{j\in \mathcal{D}}d_{j}c_{i(j)j}+M\sum_{e\in T}c_{e} , is minimized. We present a primal-dual 6.55-approximation algorithm for the ConFL problem which improves the previous primal-dual 8.55-approximation algorithm given by Swamy and Kumar (Algorithmica 40:245–269, 2004).     

Women’s Strategic Responses to Intimate Partner Violence: A Study in a Rural Community of Bangladesh

The objective of this study was to explore women’s strategic responses to physical violence perpetrated by an intimate partner. Twenty women from a rural area of the Narshingdi district in the Dhaka division of Bangladesh who experienced physical violence at home participated in the study. Development of the interview protocol and data analysis were carried out by applying the consensual qualitative research (CQR) method. The results showed that several themes, such as women’s responses to intimate partner violence, arose from the data. First, coping strategies to pre‐violent events included three themes: (i) leaving the scene; (ii) trying to divert attention; and (iii) preparing to protest. Women’s strategic responses to violent events consisted of four themes: (i) leaving the scene; (ii) remaining silent or no giving response; (iii) seeking help from others; and (iv) protesting against the violence. Lastly, women’s strategic responses to post‐violent events consisted of three themes: (i) temporary abstinence; (ii) verbally abusive behavior to family members; and (iii) going to the parental home. Given the findings of this study, we conclude by suggesting that more work is needed to better understand effective strategies and to draw women to institutional services to prevent violence to a greater extent.     

Challenging Nuclear: Antinuclear Movements in Postauthoritarian Indonesia

In mid-2006, the Indonesian government announced a plan to build nuclear power plants geared towards meeting soaring demands for energy in the country. After prolonged procrastination, the government is determined that time is ripe for Indonesia to go nuclear. While discussions on adopting nuclear power are steadily gaining currency among high officials and political elites, it is simultaneously being contested by an antinuclear alliance consisting of multiple groups that form an organized resistance. The organized resistance is primarily driven by suspicions that the current government does not possess the capacity to handle high-risk technology. Using combined approaches of STS and social movement studies, the paper discusses the contestation of nuclear risk discourses and how lack of trust in the government has led to the ascendancy of antinuclear movements. In situating the paper within postauthoritarian Indonesia, this paper observes how shifts towards democratic change has allowed a network of civil society groups to organize resistance against nuclear power both at the national and local levels. The paper also highlights the way in which civic epistemology guides antinuclear groups to produce popular risk assessments that confront scientific calculations of nuclear risk. Lastly, it presents a vignette of how civil society groups mobilize local resources to explore alternative energy systems that ultimately undermine the government’s nuclear ambitions.     

On the Failure Probability of Used Coherent Systems

In analyzing the lifetime properties of a coherent system, the concept of “signature” is a useful tool. Let T be the lifetime of a coherent system having n iid components. The signature of the system is a probability vector s=(s₁, s₂, …, s_n), such that s_i=P(T=X_i:n), where, X_i:n, i=1, 2, …, n denote the ordered lifetimes of the components. In this note, we assume that the system is working at time t>0. We consider the conditional signature of the system as a vector in which the ith element is defined as p_i(t)=P(T=X_i:n|T>t) and investigate its properties as a function of time.     

Revolution,war and modernization: Population policy and fertility change in Iran

Fertility trends in Iran over recent decades can be plausibly related to a number of causal factors. Population policy shifts were quite marked, and were related to political upheaval and war, which influenced both official policy and popular perceptions of the nation’s need for children. A range of developmental factors were also important. The key fertility trends to be explained include the rise to an exceptionally high level in the early 1980s (a TFR of just below 7), and the speed of the subsequent decline to a TFR of about 2.7 in 1996. As well as estimating the proximate determinants of these trends, the paper sets them in their political and developmental context. Iran’s fertility trends are then compared with those of Islamic countries of North Africa and West Asia to gain additional insights into possible causal factors. An adequate explanation of fertility change in Iran needs to draw on elements of a number of theories of fertility transition.     

Examination of Interest Inventories Based on Roe's Classification

This article describes the adaptation of two interest inventories translated into English, based on Roe's (1956) classification of occupations. In an analysis based on the responses of 181 participants, the items followed the 6 rules for interest inventory items formulated by Meir and Gati (1981). The Cronbach alpha reliability of the 8 field scores in the 2 inventories ranged between .73 and .91. A Smallest Space Analysis (SSA) on 8 field scores on the Ramak, 8 field scores on the Courses and 6 personality type scores on Holland's (1973) Vocational Preference Inventory (VPI) supported the construct validity of the inventories.