1. Prepare a “sample frame,” or large list of potential
respondents, which includes firms representing
the main sectors of the economy (agriculture,
manufacturing industry, non-manufacturing
industry, and services).
2. Separate the frame into two lists: one that
includes only large firms, and one that includes
all other firms (both lists representing the various
economic sectors).2
3. Based on these lists, and in view of reducing
survey bias, choose a new selection of these
firms from both lists to receive the Survey.