Parameter Estimation of Autoregressive Models Using the Iteratively Robust Filtered Fast-τ Method

Utilizing time series modeling entails estimating the model parameters and dispersion. Classical estimators for autocorrelated observations are sensitive to presence of different types of outliers and lead to bias estimation and misinterpretation. It is important to present robust methods for parameters estimation which are not influenced by contaminations. In this article, an estimation method entitled Iteratively Robust Filtered Fast? τ(IRFFT) is proposed for general autoregressive models. In comparison to other commonly accepted methods, this method is more efficient and has lower sensitivity to contaminations due to having desirable robustness properties. This has been demonstrated by applying MSE, influence function, and breakdown point criteria.     

On the quantile past lifetime of the components of the parallel systems

ABSTRACT

Let T_{1: n} ? T_{2: n} ? ??? ? T_{n: n} be ordered lifetimes of components of a parallel system. In this article, the α-quantile past lifetime from the failure of the component with lifetime T_{r: n} provided that the system has failed at or before time t has been introduced. Then, some properties of this measure have been studied.     

On the Percentile Residual Lifetime of Parallel Systems

In this paper, we consider a parallel system consisting of n components. Then, the percentile residual lifetime of the system given survival of at least n ? r + 1, r = 1, 2, …, n component(s) has been introduced, and some properties of this measure have been investigated. We show that the system accommodates decreasing percentile residual lifetime function, provided the components have increasing hazard rate functions. Different parallel systems have been compared with each other in terms of the introduced measure. Furthermore, behavior of the percentile residual lifetime of the system and the components have been compared in terms of some reliability notions. Also, a characterization result has been presented.     

Estimation of monotone bivariate quantile residual life

The bivariate quantile residual life function can play an important role in statistical reliability and survival analysis. In many situations assuming a decreasing form for it is recommended. Here, we propose a new non-parametric estimator of this measure under such restriction. It has been shown that the new estimator is consistent and, with proper normalization, weakly converges to a bivariate Gaussian process. A simulation study shows that the proposed estimator is an alternative to the unrestricted estimator when the bivariate quantile residual life is decreasing. Finally, the new estimators are applied to two real data sets.     

Attitude and Propensity to Divorce in Iran: Structural and Ideational Determinants

Divorce has been increasing worldwide, even in societies where religious impediments to it are strongest. In the Islamic Republic of Iran, divorce rates have risen rapidly since the mid-1990s. In this article, we investigate the attitude and propensity of young Iranians toward divorce and relate these attitudes and propensities to structural and ideational factors. The data are drawn from a survey of 720 married people ages 15 to 29 conducted in the city of Tehran in 2014. The results show that almost half of respondents approved of divorce as a solution for marital problems and one fifth of them have high propensity to divorce. Multivariate analyses indicate that approval of and high propensity toward divorce are significantly associated with ideational factors—namely individualism, secularism, and gender egalitarian views—and structural factors—including education, wife’s employment, and household economic insecurity—even after controlling for demographic variables. We discuss the implications of these findings for the understanding of marital stability in this rapidly changing context.     

Socio‐cultural Adaptation of Second‐generation Afghans in Iran

The long‐term settlement of Afghan immigrants in Iran, along with their high fertility, has produced an important shift in the composition of their population with the emergence of a “second generation”. This article aims to examine how second‐generation Afghans have adapted to the host society and to what extent their adaptation patterns have correlated with demographic and contextual factors. The data is drawn from the 2010 Afghans Adaptation Survey which covered 520 second‐generation Afghans. Results revealed that second‐generation Afghans have a variety of adaptation patterns. Integration is the most prevalent pattern of adaptation and acculturation (which is observed among 35.8 per cent of respondents) followed by separation (33.3%), assimilation (17.1%) and marginalization (13.8%). Our multivariate analysis showed that such socio‐demographic factors as gender, education, ethnicity, perceived discrimination, family context, neighbourhood characteristics, length and city of residence are associated with their adaptation patterns.

Policy Implications

• Successful implementation of policies and durable solutions for Afghans in Iran rests on the diversity of the adaptation patterns of their second‐generation.
• Restriction on employment opportunities has led to downward assimilation and marginalization of some of the Afghans in Iran. Improvement in labour laws would promote the integration of Afghans in the society.
• Afghan females have relatively better access to a gender‐equitable environment in Iran than they do in Afghanistan, and are less willing to return to their homeland. The Government of Afghanistan should improve service and security provisions for women to ensure their voluntary repatriation.

     

Marriage and Family Formation of the Second‐Generation Afghans in Iran: Insights from a Qualitative Study

In 2006, around 1.2 million documented Afghans remained in Iran, of whom half were second generation. This paper is based on the results of a qualitative study conducted in three settings: Tehran, Mashhad and Isfahan, and draws on data collected via 80 in‐depth interviews and six focus group discussions with second generation Afghans in Iran. The aim of the paper is to explore the adaptation of second‐generation Afghans in Iran, particularly in relation to marriage and family formation. The results show that educational achievements and occupational skills of the second‐generation Afghans in Iran facilitated their adaptation to the host society, and inspired different marriage and family behaviors and aspirations in comparison with the first generation.