업종별로 1차 층화하고 다시 종사자 수를 기준으로 2차 층화하였으며, 표본 배분에는 네이만 배분법을 적용하였다.
The first stratification by industry was performed, and the second stratification was performed based on the number of employees, and the Neimann distribution method was applied to the sample distribution.