Simultaneous Closeness of k-Records

In this article, we study the simultaneous Pitman closeness of upper (and lower) k-records to a common parameter of the parent distribution and obtain general expressions for the corresponding probabilities. Since the usual record values are contained in the k-records, the corresponding results for the usual records can be deduced as special cases. The results are then applied to location-scale families with an emphasis on population quantiles. Exact expressions are derived for some common distributions such as exponential and uniform. In each case, the simultaneous closest k-record to a population quantile is determined.     

Structural changes in high performing minority and nonminority banks in the deregulated banking environment

This study considers the changes that have occurred in the balance sheets of high-performance minority-owned banks during the period 1981–1988 and compares them to changes in the balance sheets of high-performance nonminority-owned banks. The changes are analyzed using two methodologies: decomposition analysis and a t-test of the mean differences of the balance sheet and of its component parts. The study examines changes in total assets, total liabilities, and the balance sheets as a whole, and then disaggregates the assets and liabilities to determine where the changes occurred in each group of banks. The findings show statistically significant differences in the average proportions of assets and liabilities between the two groups: minority banks held more cash than nonminority banks, fewer loans, more premises, a higher volume of other assets, more common stock and lower undivided profits. Although the wide differences in the structural changes of assets and liabilities began to narrow in 1985–1987, the analysis indicates the differences may again be increasing between the two groups.     

Team selection for prediction tasks

Given a random variable \(O \in \mathbb {R}\) and a set of experts \(E\), we describe a method for finding a subset of experts \(S \subseteq E\) whose aggregated opinion best predicts the outcome of \(O\). Therefore, the problem can be regarded as a team formation for performing a prediction task. We show that in case of aggregating experts’ opinions by simple averaging, finding the best team (the team with the lowest total error during past \(k\) rounds) can be modeled with an integer quadratic programming and we prove its NP-hardness whereas its relaxation is solvable in polynomial time. At the end, we do an experimental comparison between different rounding and greedy heuristics on artificial datasets which are generated based on calibration and informativeness of exprets’ information and show that our suggested tabu search works effectively.     

Integrating welfare economics in social work curriculum: a Malaysian case

This paper makes a case for why welfare economics should be integrated and taught in social work courses, taking Malaysia a case in point. This is mainly a conceptual paper and secondary data are used to further support the arguments. Commencement of professional social work in Malaysia dates to 1946, to address the socio-economic problems of the Malaysians and migrants at that time. Social workers need a multi-pronged approach that is crucial to address the human problems that includes psychological, social, political, cultural and economic at micro and macro levels. Most of the problems referred to the social workers stem from poverty, unemployment, low access to material resources and corrupt governance practices coupled with unjust economic policies. Keeping in view the diverse economic needs and strengths of the clients referred to social workers, it is necessary that social workers are equipped with appropriate skills that include broader understanding about political economy. This paper argued that integration of welfare economics in the social work curricula is an urgent need considering the Malaysian economic development, austerity measures and the proactive role that social work as a human rights profession could play in the Malaysian society.     

On estimation of stress–strength parameter using record values from proportional hazard rate models

ABSTRACT

Based on record values, this article deals with inference for stress–strength reliability, R = P(X < Y), where the distributions of X and Y follow proportional hazard rate models but having different parameters. Maximum likelihood estimator, uniformly minimum variance unbiased estimator, Bayes estimator, and different confidence intervals for R are obtained. Numerical computations and simulation study are presented for illustrative purposes.     

Block censoring scheme with two-parameter exponential distribution

This paper deals with a new censoring scheme, called ‘Block Censoring’ which reduces considerably the total time on test in the life testing experiments with respect to the common used experimental tests such as rightly censored data. This new scheme is analysed when the lifetimes of products follow the two-parameter exponential distribution. Specially, it is proved that the respective spacings are independently distributed exponential. The problem of estimating parameters is investigated in details.A Monte Carlo simulation is conducted for obtaining the optimal block censoring scheme in the sense of the shortest expected test time. Finally, a real data set on times to breakdown of an insulating fluid between electrodes from Nelson [Applied life data analysis. New York: Wiley; 1982. p.105] is analysed.     

Comparing the fisher information in record values and iid observations

In a number of experiments, such as destructive stress testings, sampling is conducted sequentially. In such experiments, in which destruction of sample units may be expensive, one may wonder if it is more economical to observe n lower record values than to observe n iid observations from the original distribution. In this paper, we establish some general results concerning the comparison of the amount of the Fisher information contained in n record values and inter-record times with that contained in n iid observations from the original distribution. Some specific common distributions are classified according to this criterion.     

Comparison among non parametric prediction intervals of order statistics

Abstract

In this article, we are interested in conducting a comparison study between different non parametric prediction intervals of order statistics from a future sample based on an observed order statistics. Typically, coverage probabilities of well-known non parametric prediction intervals may not reach the preassigned probability levels. Moreover, prediction intervals for predicting future order statistics are no longer available in some cases. For this, we propose different methods involving random indices and fractional order statistics. In each case, we find the optimal prediction intervals. Numerical computations are presented to assess the performances of the so-obtained intervals. Finally, a real-life data set is presented and analyzed for illustrative purposes.