Browsing by Author "Steel, S. J."

Now showing 1 - 4 of 4
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    Identifying secondary series for stepwise common singular spectrum analysis
    (Operations Research Society of South Africa, 2013) Viljoen, H.; Steel, S. J.
    Common singular spectrum analysis is a technique which can be used to forecast a primary time series by using the information from a secondary series. Not all secondary series, however, provide useful information. A first contribution in this paper is to point out the properties which a secondary series should have in order to improve the forecast accuracy of the primary series. The second contribution is a proposal which can be used to select a secondary series from several candidate series. Empirical studies suggest that the proposal performs well.
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    Importance of external environmental labour-related risk factors for financial investment decision-making
    (AOSIS, 2002) Mostert, J. H.; Steel, S. J.; Mostert, F. J.
    External environmental labour-related risk factors influence the relationship between management and the work force of an enterprise. It is therefore of prime importance to consider these labour-related risk actors in order to be able to take a comprehensive financial investment decision. The risk factors concerned come from the political, economic, social and technological environments. The views of the participating investment practitioners (who are active in the long-term insurance industry) regarding these aspects are analysed against the background of relevant literature. The responses with reference to these labour-related risks in manual and knowledge worker enterprises are presented simultaneously and significant similarities and differences are highlighted.
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    Portfolio management practices of investment practitioners active in the long-term insurance industry
    (AOSIS, 2001) Mostert, J. H.; Steel, S. J.; Mostert, F. J.
    In the long-term insurance industry, sound financial investment decisions depend largely on the portfolio management practices of the investment practitioners concerned. The ability of the investment practitioners to make well-informed decisions, as well as the strategies and policies underlying portfolio management practices, are the main issues of this research. Important correlations amongst various aspects of the financial investment decisionmaking process, as well as their association with the general information pertaining to the long-term insurers (which were disclosed during the empirical study), emerge in the closing section of this paper. The conclusions should be of prime interest to long-term insurers as well as investment practitioners who are working in that industry.
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    Variable selection in multiple linear regression : the influence of individual cases
    (Operations Research Society of South Africa, 2007) Steel, S. J.; Uys, D. W.
    ENGLISH SUMMARY : The influence of individual cases in a data set is studied when variable selection is applied in multiple linear regression. Two different influence measures, based on the Cp criterion and Akaike’s information criterion, are introduced. The relative change in the selection criterion when an individual case is omitted is proposed as the selection influence of the specific omitted case. Four standard examples from the literature are considered and the selection influence of the cases is calculated. It is argued that the selection procedure may be improved by taking the selection influence of individual data cases into account.