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.

     

On the theory of macroeconomic policy

Summary Jan Tinbergen originated the theory of policy in the 1950s. Here I apply it to contemporary macroeconomics. The two standard instruments of short-run demand management cannot achieve the two usual targets, full employment and price stability. With respect to those goals, these two instruments are collinear, except for small and transient effects on foreign exchange rates. But the mix of fiscal and monetary policies, relative to one another, does have important effects on the composition of national output, as between investment and consumption.I point out that policy-makers, like portfolio managers, should diversify the instruments they use when they are uncertain of their effects. I discuss some pitfalls in the empirical estimation of policy effects, especially possible misinterpretations of simple correlations, and I note that policy rules cannot be invariant to changes in macroeconomic structure. I argue that policy rules should involve responses to new information and in practice allow discretion. Finally, I suggest that Tinbergen's theory of policy needs to be extended to policy coordination among nations.Third Tinbergen Lecture delivered on October 20, 1989, in Utrecht for the Royal Netherlands Economic Association.     

Discriminating Among Alternative Theories of the Multinational Enterprise

Recent theoretical developments have incorporated endogenous multinational firms into the general–equilibrium model of trade. One simple taxonomy separates the theory into "vertical" models, in which firms geographically separate activities by stages of production, and "horizontal" models, in which multiplant firms duplicate roughly the same activities in many countries. The authors nest a horizontal and a vertical model within a hybrid (unrestricted) "knowledge–capital model" and estimate the specifications with data on US foreign direct investment activity. In the nested econometric tests, the data sample cannot distinguish statistically between the unrestricted model and the restricted horizontal model, indicating that the latter captures virtually all of the determinants of FDI. The tests overwhelmingly reject the vertical model.     

Flunking economics?

Economists are in revolt over President Clinton's health care reform proposal. Many contend that the Administration is abandoning free-market principles and embracing price controls that could have disastrous consequences. But others argue that traditional rules of supply and demand don't apply to the health care sector.