Local influence diagnostics for the retrospective problem in sequential analysis : Diagnostics d'influence locale concernant le pfofil rétrospectif dans l'analyse séquentielle de population

Equation (5) can be used to estimate the Na,y s for all ages and years if the NA,y s (numbers at the oldest age A for all years) and the survivors in the last year Y , the Na,Y s, are both known. [...] Changes to the catches in the direction of 6 smax in panel b of Figure 11 will increase ρ towards zero and reduce the retrospective pattern in F̄. [...] The value of h we selected was smaller in absolute value than the local approximation of −8.5 because of the nonlinearity in the inßuence curve. [...] As with the M perturbations, the inßuence curve in the direction of smax is reasonably linear within the 8 range of h we considered. [...] Although this is obviously not as desirable as identifying 9 the components that are at the root of the retrospective pattern, the determination of which components that are unlikely to have caused the problem is nevertheless useful.