An extension of mixed estimation,with an application to forecasting new product growth

This paper extends the mixed estimation technique to handle a case in which the coefficients of a set of linear constraints are known nonlinear functions of an unknown parameter vector for which an extraneous unbiased estimate is available. This novel form of the mixed estimation technique is illustrated by applying it to the Bass innovation/diffusion model of new product growth. It is suggested that this is superior to the traditional method whereby managerial intuition is incorporated into this type of model, and is an attractive alternative to recently-suggested Bayesian methods.I thank an anonymous referee for helpful comments and references.     

L'approccio di B. De Finetti per la riassicurazione individuale proporzionale. Modelli semplificati e considerazioni operative

Viene studiato il problema della determinazione della strategia riassicurativa ottima in caso di riassicurazione individuale proporzionale, secondo l'approccio media-varianza. In particolare si analizzano alcuni modelli semplificati nei quali si raggruppano le polizze di un portafoglio sulla base di certe caratteristiche di omogeneità; ciò consente di ridurre in maniera sensibile la complessità dei calcoli previsti nella procedura generale. Completano il lavoro considerazioni di carattere operativo.

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Summary The optimal reinsurance strategy for the proportional reinsurance problem in a meanvariance framework is investigated. In order to simplify the algorithmic complexity, simple models based on the aggregation of portfolio policies are studied. Some operational remarks are added.

     

Banks and the stability of the international financial system

Summary Does today's banking scene pose a potential threat to the stability of the international financial system? The article discusses three possible sources of vulnerability of the international banking system: a major bank failure causing a general banking crisis via the extensive interbank linkages; the systemic risks allegedly inherent in certain new (as well as traditional) financial products; and the impact of external events such as debt crises, violent swings in exchange or interest rates, deregulation and recession. The author's conclusion is twofold: systemic risks clearly exist, but the probability of a major banking crisis tends to be greatly exaggerated. Banks not only survived the various crises of the seventies and eighties; they also learned in the process. Capital and reserves have been strengthened, provisions for country risk and for general contingencies have increased, supervision has been tightened and it is exercised on a comprehensive as well as a world-wide consolidated basis (i.e. including all contingent and off-balance liabilities, and all offshore activities). Assuming reasonably intelligent policies on the part of the monetary authorities and adequate international coordination, a general banking crisis can be avoided. Official rescue operations do, however, raise difficult questions of an ethical, political and economic nature.