… Do as the Romans do. A model of conformity with the endogenous formation of preferences

This note is an answer to a previous model on conformity in public goods contributions developed by Carpenter (2004), where a population evolution is allowed according to the standard replicator dynamic (Taylor and Jonker, 1978, Maynard Smith, 1982). To confirm his theoretical prediction, Carpenter developed an experiment showing that free riding actually grows faster when agents have the information necessary to conform. The model and the experiment are, however, inherently different, for the time scales of the model are not able to capture the short run convergence of behavior in the experimental laboratory.We here present a model of conformity which offers the same laboratory results as Carpenter without resorting to evolutionary models, and also gives agents the chance to adopt different strategies implying various levels of cooperation.     

Multi-ethnic school environment from the school leader’s perspective: challenges and approaches to improve multi-cultural competency among teachers in Malaysia

This study aims to identify the challenges and approaches to improve a multicultural competency among teachers in multi-ethnic schools environment based on school leaders’ perspective. Data collection method used in this study is qualitative method. A total of nine school leaders from the states of Kedah, Penang, and Perak were included in the interview session. The results of this study show that the challenges faced by teachers in practicing the multicultural competency are lack of experience toward cultural diversity. A late exposure to cultural diversity makes it difficult for teachers to accept and adapt in a multi-ethnic school environment. The approaches suggested by school leaders to improve the multicultural competency are as follows: (1) Courses on cultural diversity should be organized to enhance the knowledge about cultural diversity; (2) the development of more open and better policy for education system in Malaysia in order to prepare teachers with a higher multicultural competency for teaching students from diverse ethnic and cultural groups; (3) an early exposure to cultural diversity in order to increase the multicultural competency, especially during teaching practicum.     

Estimation of the means of the bivariate normal using moving extreme ranked set sampling with concomitant variable

The estimation of the means of the bivariate normal distribution, based on a sample obtained using a modification of the moving extreme ranked set sampling technique (MERSS) is considered. The modification involves using a concomitant random variable. Nonparametric-type methods as well as the maximum likelihood estimation are considered. The estimators obtained are compared to their counterparts based on simple random sampling (SRS). It appears that the suggested estimators are more efficient. Also, MERSS with concomitant variable is easier to use in practice than the usual ranked set sampling (RSS) with concomitant variable. The issue of robustness of the procedure is addressed. Real trees data set is used for illustration.     

Two-Stage Variables Acceptance Sampling Plans Using Process Loss Functions

In this article, a variable two-stage acceptance sampling plan is developed when the quality characteristic is evaluated through a process loss function. The plan parameters of the proposed plan are determined by using the two-point approach and tabulated according to various quality levels. Two cases are discussed when the process mean lies at the target value and when it does not, respectively. Extensive tables are provided for both cases and the results are explained with examples. The advantage of the proposed plan is compared with the existing variable single acceptance sampling plan using the process loss function.     

On the Bayes estimators of the parameters of size-biased generalized power series distributions

ABSTRACT

In this paper, we derive the Bayes estimators of functions of parameters of the size-biased generalized power series distribution under squared error loss function and weighted square error loss function. The results of size-biased GPSD are then used to obtain particular cases of the size-biased negative binomial, size-biased logarithmic series, and size-biased Poisson distributions. These estimators are better than the classical minimum variance unbiased estimators in the sense that they increase the range of the estimation. Finally, an example is provided to illustrate the results and a goodness of fit test is done using the maximum likelihood and Bayes estimators.     

Testing variance components in balanced linear growth curve models

It is well known that the testing of zero variance components is a non-standard problem since the null hypothesis is on the boundary of the parameter space. The usual asymptotic chi-square distribution of the likelihood ratio and score statistics under the null does not necessarily hold because of this null hypothesis. To circumvent this difficulty in balanced linear growth curve models, we introduce an appropriate test statistic and suggest a permutation procedure to approximate its finite-sample distribution. The proposed test alleviates the necessity of any distributional assumptions for the random effects and errors and can easily be applied for testing multiple variance components. Our simulation studies show that the proposed test has Type I error rate close to the nominal level. The power of the proposed test is also compared with the likelihood ratio test in the simulations. An application on data from an orthodontic study is presented and discussed.     

A note on the mean residual life of a coherent system with a cold standby component

In this paper, we investigate the effect of a cold standby component on the mean residual life (MRL) of a system. When the system fails, a cold standby component is immediately put in operation. We particularly focus on the coherent systems in which, after putting the standby component into operation, the failure of the system is due to the next component failure. For these systems, we define MRL functions and obtain their explicit expressions. Also some stochastic ordering results are provided. Such systems include k-out-of-n systems. Hence, our results extend some results in literature.     

Information matrix for a mixture of two inverse gaussian distributions

In this paper, Fisher information matrix about the five parameters ρ, μ_:1, μ², λ¹and λ²of a mixture of two Inverse Gaussian density functions is obtained. The Leguerre-Gauss quadrature formula is used to evaluate the essential integral on which the twenty five elements of the information matrix are based. Results involving the computation of the information about p are compared with those involving both the power series expansion and Simpson's method of integration. Laguerre-Gauss quadra-ture was found to lead to good approximations as compared with other methods. It was therefore chosen for the computations of the elements of the information matrix.     

Economic burden of tuberculosis and its coping mechanism at the household level in Pakistan

Despite the availability of free medicines under the Directly Observed Treatment Short-course (DOTS) strategy, the treatment of tuberculosis (TB) still involves high costs that push people into poverty. This study aims to assess the resulting economic burden of TB and examine the coping mechanisms practiced at the household level in Pakistan. A cross-sectional study was conducted at TB centers by interviewing 269 patients. Statistical tests and binary logistic regression were used to explore the relationship between catastrophic health expenditures (CHE) and socio-economic factors. Results show that the incidence and intensity of CHE were higher for households in the lower income-quintile. Several coping strategies were practiced and varied among the different income-quintiles. The independent determinants of CHE were as follows: age >40 years, male-patient, location, earner-ratio, patient as the earner, caretaker visits, treatment delay, and co-morbidity. It is recommended that health policymakers develop post-MDGs TB-control strategies to ensure free TB-services with financial protection around the globe.