Summary Process control schemes using a simple scoring system are presented for controlling the mean of a normal distribution in the one and two sided case. The average run lengths of the schemes are simpler to compute than those of cumulative sum schemes, and for small deviations in the process mean the schemes are considerably more sensitive than Shewhart schemes. Some examples and comparisons are given.

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Certain continuous production processes and early warning systems must be inspected in order to detect failures that would otherwise not be apparent. An optimal inspection policy is a sequence of inspection times which minimizes the average cost per inspection cycle relative to some cost model. Under both an existing cost model, and a new cost model proposed in this paper, the computation of such policies is difficult. Three sub-optimal inspection policies are proposed, each, like the optimal policy, having decreasing times between successive inspections when the time to system failure has increasing hazard rate. Numerical comparisons are given for both cost models in the case of Weibull failure times.reliability: inspection, inventory/production: policies, maintenance

England). A methodology for evaluating size at birth. Acta Paediatr Scand, Suppl. 319 26.Data from the Swedish Medical Birth Registration, 1977-78, were utilized to develop methods of calculating reference standards for evaluating size at birth. Using the clinical information available, a 'healthy' sub-group was extracted. The individual distributions of birthweight (BW), birth length (BL) and birth headcircumference (BHc) at each week of gestational age (GA) were modelled following some truncation of their ranges. Application of the Box-Cox power family of transformations was generally found to improve the normality of the data. Certain percentages (such as 2.28, 50 and 97.72) -re linked through a smoothing dwice. Features of the results include a positively skewed BW distribution in most GA weeks, a normal distribution of BL and BHc at term, a larger relative variation in BW at lower GA than at term, and a distinct sigmoid shape of the median and other BW curves. Compared with flve commonly quoted standards, the present data show the least deceleration in the fullterm region. Disregarding the clinical information, 'primary' sub-groups were also extracted using desomposing techniques. These gave rise to similar BWlGA relationships. Using data from the WHO comparative study, the method just mentioned was applied to standardize BW and BW-specific early neonatal mortality rates. This resulted in an improved description of biological events. Key nwrds: F e d growth, birthweight, birth length, birth head circumference, gestational age, statistical modelling, neonatal mortality, reference standard.

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