The Gerber-Shiu Expected Discounted Penalty Function: An Application to Poverty Trapping

In this article, we consider a risk process with deterministic growth and prorated losses to model the capital of a household. Our work focuses on the analysis of the trapping time of such a process, where trapping occurs when a household's capital level falls into the poverty area, a region from which it is difficult to escape without external help. A function analogous to the classical Gerber-Shiu expected discounted penalty function is introduced, which incorporates information on the trapping time, the capital surplus immediately before trapping and the capital deficit at trapping. Given that the remaining proportion of capital upon experiencing a capital loss is Beta(α,1)-distributed, closed-form expressions are obtained for quantities typically studied in classical risk theory, including the Laplace transform of the trapping time and the distribution of the capital deficit at trapping. In particular, we derive a model belonging to the generalised beta (GB) distribution family that describes the distribution of the capital deficit at trapping given that trapping occurs. Affinities between the capital deficit at trapping and a class of poverty measures, known as the Foster-Greer-Thorbecke (FGT) index, are presented. The versatility of this model to estimate FGT indices is assessed using household microdata from Burkina Faso's Enqu\^ete Multisectorielle Continue (EMC) 2014.