Appendice statistica. La metodologia del campionamento

This appendix deals with the sampling procedures applied to the study of the construction firms in Italy. Six independent samples were selected in six Italian Towns, constituting a reasoning sample of the geography of the Sector: Rome was investigated in a pilot survey. A univariate stratification procedure was applied to the variable “number of hired workers” estimated for each firm. For each stratum, weights were calculated as means of monthly observations. The results of this approach were compared with those obtained from a dynamic model of the firms’ population. The relative efficiency of this procedure was estimated with respect to the traditional sampling procedure based on a static specification.