สำมะโนธุรกิจและอุตสาหกรรม พ.ศ. 2565 อุตสาหกรรมการผลิต: ภาคเหนือ

61 Appendix A : Sample Design 1 . Establishments with 1 – 10 persons engaged The stratified systematic sampling was adopted for the survey . Bangkok and each province were constituted a stratum . Each Thailand Standard Industrial Classification ( TSIC 2009 ) and sub - size of establishment was constituted a sub - stratum . The sample unit were establishments . 1 ) stratification Bangkok and each province were constituted a stratum . There were altogether 77 strata . Each stratum was classified by TSIC 2 0 0 9 into 818 sub - stratum at 409 activity levels and in each sub - stratum was divided into 2 sub - sizes according to number of persons engaged : 1 – 5 and 6 – 10 . 2 ) Selection of Sampling Unit The sample selection of establishments was done by systematic sampling and performed separately and independently in each sub - stratum and sub - size . The total selected sampling unit were 49,952 establishments from total 398,645 establishments . Appendix A : SAMPLE DESIGN