Empirical analyses of Cagan's money demand schedule for hyper-inflation have largely ignored the explosive nature of hyper-inflationary data. It is argued that this contributes to an (i) inability to model the data to the end of the hyper-inflation, and to (ii) discrepancies between "estimated"...

We consider forecasting from age-period-cohort models, as well as from the extended chain-ladder model.  The parameters of these models are known only to be identified up to linear trends.  Forecasts from such models may therefore depend on arbitrary linear trends.  A condition for invariant...