Some Pitman closeness properties pertinent to symmetric populations

In this paper, we focus on Pitman closeness probabilities when the estimators are symmetrically distributed about the unknown parameter θ. We first consider two symmetric estimators θ?₁ and θ?₂ and obtain necessary and sufficient conditions for θ?₁ to be Pitman closer to the common median θ than θ?₂. We then establish some properties in the context of estimation under the Pitman closeness criterion. We define Pitman closeness probability which measures the frequency with which an individual order statistic is Pitman closer to θ than some symmetric estimator. We show that, for symmetric populations, the sample median is Pitman closer to the population median than any other independent and symmetrically distributed estimator of θ. Finally, we discuss the use of Pitman closeness probabilities in the determination of an optimal ranked set sampling scheme (denoted by RSS) for the estimation of the population median when the underlying distribution is symmetric. We show that the best RSS scheme from symmetric populations in the sense of Pitman closeness is the median and randomized median RSS for the cases of odd and even sample sizes, respectively.     

Application of a stochastic model to response assessments in a study of squamous cell carcinoma of the head and neck

This paper discusses the application of a stochastic model in the analysis of response assessments made at various time points in a clinical trial of patients with squamous cell carcinoma of the head and neck. The transition rates and probabilities during treatment administration are derived using maximum likelihood methods. The results are then compared with the standard analyses used in solid tumour studies. Stochastic modelling is considered to complement the standard analyses, provide a holistic approach and better explain the underlying disease process. Copyright © 2012 John Wiley & Sons, Ltd.     

Iud retention in West Pakistan and methodology of assessment

In 1967 there was a sample survey of women who had had IUD insertions in West Pakistan during the first 18 months of the Pakistan National Family Planning Program which began in July, 1965. The 12 month retention rate, including reinsertions, per 100 respondents was 56. Certain gross relationships between respondent characteristics and IUD retention were found. Respondents age 35+ and with 5+ living children and respondents who had insertions within two months postpartum had relatively high retention rates. Respondent characteristics associated with low retention rates included: age 35+ with 0–4 living children; reasons other than family planning reported as reasons for insertion; less than one-half hour travel time required to obtain insertion; not informed at time of insertion about side-effects of IUD; and insertion during last six months of 1966. Consistency of response was evaluated by reinterviewing a sample of respondents. The significance of the 43 percent non-response rate was evaluated by making further attempts to interview a sample of non-respondents.     

The Bayesian D-optimal design for simple beta regression model in two cases (both known and unknown nuisance parameter)

According to investigated topic in the context of optimal designs, various methods can be used to obtain optimal design, of which Bayesian method is one. In this paper, considering the model and the features of the information matrix, this method (Bayesian optimality criterion) has been used for obtaining optimal designs which due to the variation range of the model parameters, prior distributions such as Uniform, Normal and Exponential have been used and the results analysed.     

The role of neighborhood physical environment on mobility and social participation among people using mobility assistive technology

This paper presents a systematic literature review on the impact of the neighborhood physical environment on mobility and social participation among people using mobility assistive technology (MAT). Peer-reviewed articles from eight databases published in French or English from 1990 to 2016 were searched. Thirty studies were included in this review. Factors related to neighborhood environmental features, mobility in transit, and accessibility of homes and public buildings influenced mobility and social participation of MAT users. The majority of reviewed studies combined different types of MAT, which made the interpretation of the results challenging. Few studies included walker, cane, and crutch users. Definitions of mobility and social participation lacked consistency and were often simplistic. Future empirical research needs to examine the impact of neighborhood physical environment factors separately for different MAT users. Causality and links between mobility and social participation of different MAT users at the neighborhood level should be further explored.     

Escaping into the world of make‐up routines in Iran

Traditionally, Iranian women's use of dress and make‐up has been an arena – sometimes a battleground – for identity negotiation. The present study questions the current over‐emphasis on identity and the prevalent tendency to look for identity meanings in the use of hejab (veiling) and cosmetics. The results of fifteen interpretive in‐depth interviews with young adult women in Iran reveal that these individuals' make‐up practices are largely associated with a total immersion in the experiential, creative aspects of make‐up use and with ways to uplift their tired spirits in a monotonous environment. Make‐up routines provide these women with opportunities to escape from boredom and immerse themselves in the playful fantasies of the world of cosmetics. Despite facing various challenges, including frequent stigmatization on account of their use of make‐up, the informants in the study derive high levels of satisfaction from their make‐up practices. The study establishes that changing socio‐cultural dynamics give rise to new forms of consumption experiences in contemporary society and calls for further investigation of such experiences in women's everyday lives.     

Market structure,bank conduct and bank performance: Evidence from ASEAN

Whether banks in a concentrated market increase their profits through monopoly pricing is a question of prime concern for antitrust policies. We explore this question by introducing the role of bank conduct into the structure–performance relationship. We apply Two-step System GMM dynamic panel model to commercial banks in the Association of South East Asian Nations over the period of 1999–2014. The results indicate that the higher profits in concentrated banking industries are partially attributable to the anti-competitive conduct of banks. These findings are robust across alternative measures of market structure and bank conduct, and different time horizons. The implications of these findings require regulators to make sure that the consolidation policy for ASEAN is achieving its purpose – i.e. financial stability – and not allowing the banks to earn monopoly rents.     

Unbiased and almost unbiased ratio estimators of the population mean in ranked set sampling

In this paper we study the problem of reducing the bias of the ratio estimator of the population mean in a ranked set sampling (RSS) design. We first propose a jackknifed RSS-ratio estimator and then introduce a class of almost unbiased RSS-ratio estimators of the population mean. We also present an unbiased RSS-ratio estimator of the mean using the idea of Hartley and Ross (Nature 174:270?C271, 1954) which performs better than its counterpart with simple random sample data. We show that under certain conditions the proposed unbiased and almost unbiased RSS-ratio estimators perform better than the commonly used (biased) RSS-ratio estimator in estimating the population mean in terms of the mean square error. The theoretical results are augmented by a simulation study using a wheat yield data set from the Iranian Ministry of Agriculture to demonstrate the practical benefits of our proposed ratio-type estimators relative to the RSS-ratio estimator in reducing the bias in estimating the average wheat production.