. 2018 Aug 1;13(8):e0200606. doi: 10.1371/journal.pone.0200606

Table 1. Unweighted sample descriptive statistics.

	NIDS,2008			NIDS,2010–11			NIDS,2012			NIDS,2014–15
Variable	n	Med/ Percent	IQR/ Frequency	n	Med/ Percent	IQR/ Frequency	n	Med/ Percent	IQR/ Frequency	n	Med/ Percent	IQR/ Frequency
Men	18,617	43.8%	8,143	19,307	43.1%	8,322	21,810	43.0%	12,389	24,856	43.15%	10,725
Age class	18,541			19,293			21,780			24,808
15–24		30.7%	5,690		33.1%	6,387		32.4%	7,052		31.6%	7,839
25–34		19.7%	3,657		20.1%	3,884		21.2%	4,620		22.7%	5,642
35–44		16.6%	3,082		15.4%	2,967		15.2%	3,309		14.8%	3,678
45–54		13.8%	2,567		13.1%	2,525		12.9%	2815		12.5%	3,111
55–64		9.5%	1,766		9.4%	1,815		9.5%	2,067		9.6%	2,367
65+		9.6%	1,779		8.9%	1,715		8.8%	1,917		8.7%	2,162
Racial ascription	18,617			19,306			21,810			24,856
Black		76.6%	14,254		81.8%	15,793		81.2%	17,718		82.5%	20,500
Coloured		15.4%	2,859		13.6%	2,632		14.4%	3,133		14.1%	3,509
White		6.3%	1,182		3.3%	638		3.2%	694		2.4%	606
Asian		1.7%	322		1.3%	243		1.2%	265		1.0%	241
Education	18,510			19,270			21,725			24,763
None		13.1%	2,417		12.2%	2,357		10.8%	2,358		8.8%	2,185
Primary^*		23.9%	4,434		22.4%	4,316		20.9%	4,529		19.0%	4,706
Secondary^*		53.8%	9,950		55.8%	10,744		56.7%	12,312		56.9%	14,094
Tertiary^*		9.2%	1,709		9.6%	1,853		11.6%	2,526		15.35	3,778
Urban	18,617	50.5%	9,395	19,228	46.3%	8,897	21,810	47.4%	10,342	24,856	49.4%	12,287
Current smoking	15,507	21.1%	3,277	16,775	15.8%	2,645	19,901	14.6%	2,898	22,738	18.8%	4,226
Current alcohol use	15,504	24.3%	3,767	16,735	20.5%	3,437	18,664	23.5%	4,386	22,737	28.7%	6,532
Waist circ. [cm]	13,970	83.1	[74.2;95.4]	15,146	82.0	[72.0;96.0]	18,262	86.0	[76.0;98.7]	22,402	84.8	[74.8;98.9]
BMI [kg/m2]	13,885	24.4	[20.9;29.7]	15,122	25.0	[21.4;30.3]	18,317	25.0	[21.5;29.9]	22,324	24.8	[21.0;30.6]
BMI category^**	13,885			15,122			18,317			22,324
Underweight		6.8%	947		5.7%	863		3.9%	722		5.3%	1,193
Normal weight		47.2%	6,550		44.4%	6,714		46.0%	8,428		45.6%	10,171
Overweight		22.1%	3,066		23.9%	3,614		25.3%	4,632		22.1%	4,926
Obese		23.9%	3,322		26.0%	3,931		24.8%	4,535		27.0%	6,034
CVD history	18,617	3.7%	689	19,307	2.5%	481	21,810	3.5%	757	24,856	2.6%	649
Diagnosis of hypertension	17,141	15.7%	2,686	18,480	12.0%	2,216	21,282	16.4%	3,496	21,915	10.6%	2,330
Antihypertensive treatment	16,846	11.5%	1,932	18,268	9.2%	1,690	21,005	12.0%	2,527	23,659	13.9%	3,288
First systolic reading [mm Hg]	13,792	123	[111;139]	14,745	122	[110;136]	18,318	121	[110;135]	22,455	121	[109;135]
Second systolic reading [mm Hg]	13,732	121	[109;136]	14,622	120	[109;134]	18,306	119	[108;133]	22,446	119	[107;133]
First diastolic reading [mm Hg]	13,810	80	[71;90]	14,730	79	[71;89]	18,320	80	[72;90]	22,466	79	[71;89]
Second diastolic reading [mm Hg]	13,713	79	[70;89]	14,644	78	[70;88]	18,308	79	[71;89]	22,455	78	[70;88]

n = number of not missing values; Med = median; IQR = interquartile range. BMI = body mass index; CVD cardiovascular disease.

* Some or completed. Tertiary education includes any further training after completion of secondary education.

** Underweight: BMI < 18.5 Kg/m²; Normal Weight: 18.5 Kg/m² ≤ BMI < 25 Kg/m²; Overweight: 25 Kg/m² ≤ BMI < 30 Kg/m²; Obese: BMI > 30 Kg/m².

Note that the total number of non-missing values for some demographic variables in the NIDS samples exceeds the number of subjects actually interviewed reported in the description of survey response rates in the article. This is because the NIDS datasets incorporate demographic information on subjects not interviewed recovered from the household roster. The sampling weights provided with the datasets are calculated taking into account these individuals.