Estimation of common location parameter of several heterogeneous exponential populations based on generalized order statistics

In this article, several independent populations following exponential distribution with common location parameter and unknown and unequal scale parameters are considered. From these populations, several independent samples of generalized order statistics (gos) are drawn. Under the setup of gos, the problem of estimation of common location parameter is discussed and various estimators of common location parameter are derived. The authors obtained maximum likelihood estimator (MLE), modified MLE and uniformly minimum variance unbiased estimator of common location parameter. Furthermore, under scaled-squared error loss function, a general inadmissibility result of invariant estimator is proposed. The derived results are further reduced for upper record values which is a special case of gos. Finally, simulation study and real life example are reported to show the performances of various competing estimators in terms of percentage risk improvement.     

Parametric scalp mapping and inference via spatially smooth linear models for mismatch negativity studies

Mismatch negativity (MMN) is a neurophysiological tool that can be used to investigate various facets of comprehension. Subjects are presented with different stimuli to elicit the MMN response, which is derived from electroencephalography (EEG) signals recorded at electrodes across the brain. We propose a methodology to extend single electrode analyses of MMN data by generating smooth scalp maps of estimated experimental effects. It is shown that penalized least squares estimates of effect maps can be produced using a two step procedure involving (a) ANOVA at each electrode and (b) spatial smoothing across electrodes. A Fisher von-Mises kernel is used for smoothing scalp maps with cross-validated bandwidth selection. The methodology is applied to a case control study involving aphasics (language disordered individuals). Analysis of residuals shows possible heteroscedasticity and non-Gaussian tail behavior. For robust inference, a semiparametric multivariate approach is proposed to determine the significance of parametric maps. A variety of global and regional test statistics are developed to investigate the significance of spatial patterns in treatment effects. The methodology is seen to confirm previous findings from single electrode analysis and identifies some new significant spatial patterns of difference between controls and aphasics.     

On approximate least squares estimators of parameters of one-dimensional chirp signal

Chirp signals are quite common in many natural and man-made systems such as audio signals, sonar, and radar. Estimation of the unknown parameters of a signal is a fundamental problem in statistical signal processing. Recently, Kundu and Nandi [Parameter estimation of chirp signals in presence of stationary noise. Stat Sin. 2008;75:187–201] studied the asymptotic properties of least squares estimators (LSEs) of the unknown parameters of a simple chirp signal model under the assumption of stationary noise. In this paper, we propose periodogram-type estimators called the approximate least squares estimators (ALSEs) to estimate the unknown parameters and study the asymptotic properties of these estimators under the same error assumptions. It is observed that the ALSEs are strongly consistent and asymptotically equivalent to the LSEs. Similar to the periodogram estimators, these estimators can also be used as initial guesses to find the LSEs of the unknown parameters. We perform some numerical simulations to see the performance of the proposed estimators and compare them with the LSEs and the estimators proposed by Lahiri et al. [Efficient algorithm for estimating the parameters of two dimensional chirp signal. Sankhya B. 2013;75(1):65–89]. We have analysed two real data sets for illustrative purposes.     

Fragile Employment,Liquid Love: Employment Instability and Divorce in Israel

The study examines the relationship between the employment stability of first-marriage couples and risk of divorce in Israel. This research question is of particular interest owing to the centrality of the family in Israeli society, rising divorce rates, and increasing employment instability and “deregulation” of the labor market. We capture employment instability through two dimensions: the pattern of employment instability within couples and the continuity of each partner’s employment instability. We utilize this conceptualization to identify the link between employment instability and divorce, focusing on gender and socioeconomic resources. Data were from combined Israeli census files for 1995–2008, annual administrative employment records from the National Insurance Institute and the Tax Authority, and the Civil Registry of Divorce (N = 10,891 couples). Using a series of discrete-time event-history analysis models, findings indicate that husbands’ employment instability, especially when wives have stable employment, increases the risk of divorce; employment stability continuity has opposite gender effects on that risk; and the effect of employment instability on divorce remains significant after taking into account household economic resources. The findings reveal asymmetric gender patterns of the effect of employment instability on divorce, beyond the socioeconomic resources of the household.     

Multi dimensional system for evaluating preventive program for upper extremity disorders among computer operators

Typing is associated with musculoskeletal complaints (MSCs), caused by multiple risk factors. Although a wide variety of ergonomic intervention programs were conducted to reduce risk factors and MSC's, only few of them were found evidence based. This study aimed to test the efficacy of a workplace intervention in reducing MSC's among computer workers. 66 computer workers were assigned randomly to one of three intervention programs: ergonomic intervention including biofeedback, intervention without biofeedback and control group without intervention. The efficacy was tested by advanced assessment including; pain location and severity, posture at work, upper extremity 3D kinematics, muscle activity and psychosocial status. Working hypothesis; significant score differences will be found between the study groups which underwent ergonomic intervention and the control group on the following measures: pain complaints, upper extremity kinematics, muscle activity and psychosocial status. Significant differences were found between pre and post intervention and between research groups and the control group in pain, posture and motion. The ergonomic intervention with biofeedback had no unique contribution in comparison to other interventions. In conclusion; the proposed intervention program was found efficient for reducing pain among computer workers.     

Determinants of Life Satisfaction Among Immigrants from Western Countries and from the FSU in Israel

This study examines the integration of immigrants via their satisfaction with life in the new country. While most studies on immigrant integration have focused on objective integration parameters such as education, occupation and salary (e.g., Borjas in Friends or strangers: the impact of immigrants on the US economy. Basic Books, New York, 1990), subjective parameters have traditionally received less attention. However, in recent years it has become increasingly clear that subjective perceptions carry considerable weight in the social-integration process of immigrants (McMichael and Manderson in Human Organ 63(1):88–99, 2004; Massey and Redstone in Soc Sci Q 87(5):954–971, 2006). The study group consists of Jewish immigrants who arrived in Israel during the past two decades from two different regions of origin: Western countries, and the Former Soviet Union (FSU). All of these immigrants are generally highly educated and skilled, but they came to Israel from different societies and contrasting motives. The objective of this study is to learn about the integration of these immigrants via their satisfaction with life in Israel and to understand the factors that explain it, taking into account the differences between the immigrant groups. The findings, based on the 2007 Ruppin representative survey data (The data for this study was obtained with the support of the Israeli Ministry of Immigrant Absorption.), point to significant differences between the two immigrant groups under discussion. Western immigrants are more satisfied with their lives in Israel than FSU immigrants and have higher scores in most of the independent variables tested. The multivariate analyses for predicting an immigrant’s life satisfaction reveal that those reporting the greatest satisfaction are women, religious, with a high standard of living, with no academic education, and stronger Israeli identity (personal and as perceived by others). In addition, different variables play a role in predicting the life satisfaction for each immigrant group. This knowledge may be of service to Israeli policymakers dealing with the immigration and integration of highly skilled immigrants in Israeli society.     

Table or Circles: A Comparison of Two Methods for Choosing Among Career Alternatives

A sample of 182 young adults about to choose their college major were randomly assigned to 2 guidance methods aimed at facilitating choosing among promising career alternatives: Table‐for‐Choice and Circles‐for‐Choice. Table‐for‐Choice was perceived as more effective, but individuals' confidence in their choice was higher in the Circles‐for‐Choice condition. More factors that serve to compare and evaluate the options were listed by participants in the Circles‐for‐Choice condition. No interaction emerged between the participant's decision‐making style and the usefulness of the two methods. Both methods were perceived as more useful for participants who were already at the choice stage than for those who were only at the prescreening or the in‐depth explorations stage.