INSTITUTETS FORSKNINGSRAPPORTER

One of the major problems facing a life insurance actuary is to decide what amount of money he or she shall allocate to the company's reserve for ongoing claims. On the one hand, there is no point in building up the reserve out of proportion, on the other hand the company must limit its risk for a loss, or even ruin.

This report describes a simple model to calculate ruin- and loss probabilities in a life insurance company. It is based on the ruin probability theory presented by Beard, Pesonen and Pentikainen in their book "Risk Theory".

The model has then been developed into a Pascal program intended for a life insurance portfolio, where the user can choose to calculate any out of several parameters such as ruin probability, loss probability, suitable retention or reserve for this specific portfolio.

An overview of the program's structure is given in the Appendix

B50

Anna Johansson: Modelling the Dissolution Profile. A Study of the Release of a Drug in the Large Intestine Using Different Regression Methods. (Masters Thesis, March 1999)

It is vital that tablets are designed to release the active substance in the right area of the digestion system. To be able to predict how long and how fast a specific tablet dissolves is therefore an interesting problem. The data used here have been obtained through experiments where tablets are dissolved in vessels simulating the environment in the large intestine. The Weibull function describes adequately how the percentage released substance increases with time. The two parameters of the Weibull function (the form parameter and the scale factor) describe the slope and the delay of the curve. The methods of univariate linear regression, multivariate linear regression and partial least squares regression have been used to analyse how the two parameters depend on physical and chemical factors. The results show that the profile may be predicted quite accurately if the input data matches the ranges of the calibration data. To get a faster dissolution, variables such as percentage of polymers, percentage polymers of coating, coating solution flow, air temperature in and fluid-air flow should be increased, while variables such as percentage coating solution used of theoretical amount, nozzle pressure and air temperature out should be decreased.

B49

Marie Linder and Rolf Sundberg : Looking at process capability indices and data: Graphical statistical aspects, for application in manufacturing control.

We discuss how the capability of a manufacturing process should be presented from collected quality control data. We argue against the conventional presentation of capability in the form of estimated values of capability indices with constructed standard errors and confidence intervals. Instead we advocate a two-dimensional graphical presentation of a confidence region for mean and standard deviation jointly, of the process characteristic under study, together with a capability region in the same parameters corresponding to desired bounds for a set of capability indices regarded to be of interest. We argue that looking at the size and position of the confidence region relative to the capability region gives a good understanding of the capability and performance of the manufacturing process.

Keywords: Capability, confidence regions, tolerance.