Are the self-employed more stressed? New evidence on an old question

¹ https://www.cdc.gov/nchs/nhanes/index.htm (accessed Jan 15, 2019)

² According to the NHANES, “Each sample was assayed 3 times on 3 different days. The samples were assayed on duplicate wells, resulting in 6 data points. Sample plates were assayed in groups of 3 plates, and no 2 plates were grouped together more than once. Each assay plate contained 96 control wells with 8 control DNA samples. Assay runs with 8 or more invalid control wells were excluded from further analysis (<1% of runs). Control DNA values were used to normalize between-run variability. Runs with more than 4 control DNA values falling outside 2.5 standard deviations from the mean for all assay runs were excluded from further analysis (<6% of runs). For each sample, any potential outliers were identified and excluded from the calculations (<2% of samples). The mean and standard deviation of the T/S (relative telomere to single copy gene) ratio was then calculated normally. The data on the base pairs are not provided but NHANES suggests the formula as (3,274 + 2,413 * (T/S)). The inter-assay coefficient of variation was 6.5%” (NHANES, 2001–2002) (Needham et al., Citation2013; Needham, Rehkopf, et al., Citation2015; Verhoeven et al., Citation2014).” Hence, telomere length was measured according to the laboratory gold standard available at the time.

³ Bureau of Economic Analysis (www.bea.gov, accessed June 21, 2019) estimates 10.2 M self-employed persons in the U.S. in 2000. The U.S. Census (www.census.gov, accessed June 21, 2019) reports 186 M adults of working age that year, making the self-employed population about 5.5%.

⁴ 1 = Agriculture production; 2 = Agricultural services, forestry, and fishing; 3 = Mining; 4 = Construction; 5 = Mfg.-Food and kindred products; 6 = Mfg.-Textile mill products; 7 = Mfg.-Apparel and other finished textile products; 8 = Mfg.-Paper products, printing, publishing, and allied industries; 9 = Mfg.-Chemicals, petroleum, and coal products; 10 = Mfg.-Rubber, plastics, and leather products; 11 = Mfg.-Lumber and wood products, including furniture; 12 = Mfg.-Metal industries; 13 = Mfg.-Machinery, except electrical; 14 = Mfg.-Electrical machinery, equipment, and supplies; 15 = Mfg.-Transportation equipment; 16 = Mfg.-Miscellaneous and not specified manufacturing industries; 17 = Trucking service; 18 = Transportation, except trucking; 19 = Communications; 20 = Utilities; 21 = Wholesale Trade, Durable goods; 22 = Wholesale Trade, Nondurable and not specified goods; 23 = Retail-Department stores; 24 = Retail-Food stores; 25 = Retail-Vehicle dealers, supply and service stores; 26 = Retail-Apparel and accessory stores; 27 = Retail-Eating and drinking places; 28 = Other Retail trade; 29 = Banking and other finance; 30 = Insurance and real estate; 31 = Business services; 32 = Repair services; 33 = Private households; 34 = Lodging places; 35 = Personal services, except private households and lodging; 36 = Entertainment and recreation services; 37 = Offices of health practitioners; 38 = Hospitals; 39 = Health services, n. e. c.; 40 = Educational services; 41 = Social services; 42 = Other professional and related services; 43 = Justice, public order, and safety; 44 = Public administration, except justice, public order, safety; 45 = Military & national security; and 98 = Blank but applicable.