The article addresses a real-life problem on determining the optimum sampling interval for control of defective items in a hot rolling mill. Having observed that the pattern of appearance of mill defects indicates a geometric process failure mechanism, an economic model is developed in line with...

A key diagnostic in the analysis of linear regression models is whether the fitted model is appropriate for the observed data. The classical lack of fit test is used for testing the adequacy of a linear regression model when replicates are available. While many efforts have been made in finding...

A new test for heteroscedasticity in regression models is presented based on the Goldfeld-Quandt methodology. Its appeal derives from the fact that no further regressions are required, enabling widespread use across all types of regression models. The distribution of the test is computed using...

This paper concerns a family of univariate distributions suggested by Topp & Leone in 1955. Topp & Leone provided no motivation for this new family and by way of properties they derived only the first four integer-order moments, i.e. E(Xn) for n=1, r 2, r 3, r 4 . In this paper we provide a...

Experimental designs in which treatments are applied to the experimental units, one at a time, in sequences over a number of periods, have been used in several scientific investigations and are known as repeated measurements designs. Besides direct effects, these designs allow estimation of...

Non-rejection of a unit root hypothesis by usual Dickey & Fuller (1979) (DF, hereafter) or Phillips & Perron (1988) (hereafter PP) tests should not be taken as strong evidence in favour of unit root presence. There are less popular, but more powerful, unit root tests that should be employed...

In this paper, we make use of an algorithm of Huffer & Lin (2001) in order to develop exact prediction intervals for failure times from one-parameter and two- parameter exponential distributions based on doubly Type-II censored samples. We show that this method yields the same results as those...

Data oriented to estimate means is very important for large data sets. Since outliers usually occur, the trimmed mean is a robust estimator of locations. After building a reasonable linear model to explain the relationship between the suitably transformed symmetric data and the approximately...

Restricted likelihood was originally introduced as the criterion for the estimation of dispersion components in normal mixed linear models. Lee & Nelder (2001a) showed that it can be extended to a much wider class of models via double extended quasi-likelihood. We give a detailed description of...

In this article we examine the degree of persistence of the population series in 19 OECD countries during the period 1948-2000 by means of using fractionally integrated techniques. We use a parametric procedure due to Robinson (1994) that permits us to test I(d) statistical models. The results...