The survey covered a stratified sample of 576 firms in eight regions and ten sectors. Ancash, Arequipa, Ica, La Libertad, Lima and Callao, Piura, Puno, and Ucayali were the regions surveyed. The ten sectors and their respective ISIC-Rev 3 codes (in parenthesis) were: Food processing (1512, 1513), Textiles (171, 172), Garments (1810, 1820), Shoes (1920), Wood (2010), Chemicals (241, 242), Plastics (252), Metal Products (2811), Furniture (3610), and Other Manufacturing (3691, 3699). Firms were divided into five categories: micro (less than ten employees), Small (10-20 employees), Medium (21-49 employees), Large (50-99 employees) and Extra Large (100+).
The firm population distribution and sample were drawn from a comprehensive list of firms provided by the Ministry of Industry, Tourism, Integration and International Trade Negotiations (MITINCI).
The sample was constructed following a stratification by size, sector and location. Different probabilities of being selected were first assigned to firms classified in each of the four size categories, where the probabilities were inversely related to the number of firms in each category. This was done independently for every region. Different probabilities were used for Lima and Callao to account the high concentration of firms in that region. Once the total number of firms per size category was calculated, a second adjustment was applied, this time to take into account an expected high probability that entrepreneurs would decline being interviewed. These two adjustments give a sample distributed across all eight regions (and sizes), where Lima and Callao accounted for 70 percent of the total sample and the remaining regions for 30 percent. A third and final step was to distribute the sub-sample across sectors for each region. This sector distribution followed the population distribution pattern inside each region.
