Steady-state behaviour of serial queueing processes with impatient customers

This paper considers the steady-state behaviour of serial queueing processes with impatient customers having random selection for service, Poisson arrivals and exponential service times where the waiting space is infinite as well as finite. The expressions for the steady-state solution and mean queue length have been derived whenever the queue-discipline is first-come,first-served     

Bayes estimators in the presence of a guess value

The paper deals with the problem of parameter estimation in the presence of a guess value and attempts to justify the use of Bayes estimators as an alternative to ordinary shrinkage estimators. Finally, certain Bayes estimators of exponential parameters are obtained under type II censoring, and these are compared with the corresponding MLEs and ordinary shrinkage estimators using a Monte Carlo study.     

Australian public relations: status at the turn of the 21st century

Since its inception, public relations in Australia has grown in professional stature, status, education, research, and practice. As these trends progress, visibility of the profession is becoming steadily more pronounced in the industry, education, and public domain. Over the last two decades the Public Relations Institute of Australia together with its strategic alliances have made many changes, structurally, strategically, and academically towards the professional growth of public relations. This article briefly discusses the views of the Public Relations Institute of Australia and offers a snapshot of two surveys[1] on professional practice and related issues. Although direct comparisons are not meant to be made from these studies, both surveys offer insights into aspects of Australian public relations. Whereas mixed findings and scenarios are evident, and the surveys highlight areas for further development, the profession, with close attention to existing threats, is poised to grow in Australia.Raveena Singh is program director and senior lecturer at the University of Canberra (Australian Capital Territory) and Rosaleen Smyth is senior lecturer and public relations coordinator at Deakin University (Victoria). Both authors are coeditors of the Asia Pacific Public Relations Journal.     

Modelling spatial-temporal covariance structures in monocropping barley trials

In long-term trials, not only are individual plot errors correlated over time but there is also a consistent underlying spatial variability in field conditions. The current study sought the most appropriate covariance structure of errors correlated in three dimensions for evaluating the productivity and time-trends in the barley yield data from the monocropping system established in northern Syria. The best spatial-temporal model found reflected the contribution of autocorrelations in spatial and temporal dimensions with estimates varying with the yield variable and location. Compared with a control structure based on independent errors, this covariance structure improved the significance of the fertilizer effect and the interaction with year. Time-trends were estimated in two ways: by accounting the seasonal variable contribution in annual variability (Method 1), which is suitable for detecting significant trends in short data series; and by using the linear component of the orthogonal polynomial on time (year), which is appropriate for long series (Method 2). Method 1 strengthened time-trend detection compared with the method of Jones and Singh [J. Agri. Sci., Cambridge 135 (2000), pp. 251-259] which assumed independence of temporal errors. Most estimates of yield trends over time from fertilizer application were numerically greater than the corresponding linear trends estimated from orthogonal polynomials in time (Method 2), reflecting the effect of accounting for seasonal variables. Grain yield declined over time at the drier site in the absence of nitrogen or phosphorus application, but positive trends were observed fairly generally for straw yield and for grain yield under higher levels of fertilizer inputs. It is suggested that analyses of long-term trials on other crops and cropping systems in other agro-ecological zones could be improved by taking spatial and temporal variability into account in the data evaluation.     

On inverse sampling without replacement

The inverse sampling (due to Haldane, 1945) was proposed for random sampling with replacement draws when “the numberr of successes in the sample until the process of drawing is stopped” is prefixed. In this paper an extension of that result is proposed when the draws are obtained via random sampling without replacement.     

Estimation of mean and variance of stigmatized quantitative variable using distinct units in randomized response sampling

Received: April 6, 1998; revised version: July 12, 1999     

General class of estimators in multi-character surveys

In this paper, a general class of estimators for the estimation of a finite population total in multi-character surveys is proposed. It is shown that the estimators proposed by Arnab (2002), Amahiaet al. (1989) and Bansal and Singh (1985) are the special cases of the proposed class of estimators. The proposed class of estimators is always more efficient than the estimator proposed by Rao (1966).     

Wage determination in U.S. manufacturing 1958–1976: A collective bargaining approach

This paper presents a cross-section collective bargaining approach to the analysis of inter-industry wage movements of production workers in U.S. manufacturing over the period 1958–1976. A Hicksian model is used to classify the determinants of wage change according to their likely influence on the concession and strike costs of management and unions. Three variables which are classified as management concession and strike costs are consistently significant in empirical testing: change in value productivity, labor intensity, and the profit rate. On the basis of this finding it is suggested that inter-industry wage changes are generally a function of management concession costs. The authors acknowledge the helpful comments of an anonymous referee.     

Estimation of pinnule area in chickpea leaves: an errors-in-variables approach

The pinnule area of a chickpea leaf is estimated using its pinnule length and width. A number of regression models with andwithout measurement errors in the pinnule length and width are compared. The relationship was estimated as the pinnule areaequals 0.632 times the product of the pinnule length and width. Based on a sample of 80 pinnules, this relationship showed less than 5% difference from observed values of the pinnule area in 50% of the pinnules, less than 10% in 80% of the pinnules, and less than 15% in 92.3% of cases.