Appendice metodologica. L’indagine panel nella seconda occasione: note sul campione e sulle stime

The paper reports the description of second wave of a longitudinal survey of textile and clothing firms in Emilia-Romagna (Italy), which was conducted using a “replenished” panel survey to produce reliable cross-sectional estimates. The firms (sampling units) were stratified according to size and age, and in all phases, dead and/or emigrated firms were considered as having already left the sample, while new units selected from newborn and immigrant firms, were considered as having already entered the sample. Population dynamics change firm composition over time and the methods of cross-sectional estimation must be adapted to the longitudinal features of the samples.