Abstract
The aim of this paper is to illustrate primarily the suitability and secondly the ability of both PHM and ‘two-sample’ tests in answering problems in the reliability field. The findings stress the fact that ‘two-sample’ tests should be preferred for comparison purposes and PHM for modelling the behaviour of the equipment in the presence of various factors. Copyright © 1991 John Wiley & Sons, Ltd.

Abstract
This paper deals with the two-dimensional cutting problem in which the pieces involved in the cutting process are rectangles and the number of times a piece may appear in a cutting pattern is bounded. A modified algorithm, which is an improved version of Wang's algorithm, is presented. The computational performance of both algorithms is illustrated and compared by tests applied to a large number of randomly generated problems. The algorithms were implemented in a microcomputer. © 1990.

Abstract
Proportional hazards modelling is a powerful technique which can be used to investigate the effects of various explanatory variables on the life length of equipment. In this paper the analysis of aircraft cargo door complaints is considered, as this can cause serious delay problems. Particular attention is given to the assumptions supporting the application of the model. Consideration is given to problems in the choice of the appropriate basic metric time, definition of covariates and adapting the methodologies to this particular problem. Emphasis is placed upon the validation of the results by attempting several different structures of the dependent variables. Copyright © 1989 John Wiley & Sons, Ltd.