Table 1

Sample characteristics of respondents at recruitment by wave

Characteristics	Wave 1 (2006) (n=3452)		Wave 2 (2007–2008) (n=3586)		Wave 3 (2009) (n=4172)		Wave 4 (2011–2012) (n=4070)		Wave 5(2013–2015) (n=2775)		Total (n=9047)
Characteristics	n	%	n	%	n	%	n	%	n	%	n	%
Age group
18–24	40	1.2	33	0.9	75	1.8	58	1.4	40	1.4	151	1.7
25–39	604	17.5	588	16.4	807	19.3	730	18.0	462	16.7	1678	18.6
40–54	1708	49.5	1811	50.5	1970	47.2	1837	45.2	1148	41.4	4025	44.5
55+	1100	31.9	1154	32.2	1320	31.6	1442	35.5	1121	40.5	3186	35.2
Sex
Male	3293	95.4	3411	95.1	3977	95.3	3888	95.5	2627	94.7	8841	95.0
Female	159	4.6	175	4.9	195	4.7	182	4.5	148	5.3	465	5.0
City
Beijing	521	15.1	608	17.0	586	14.1	531	13.1	517	18.6	1238	13.7
Shenyang	401	11.6	553	15.4	619	14.8	570	14.0	510	18.4	1488	16.5
Shanghai	708	20.5	728	20.3	670	16.1	675	16.6	665	24.0	1370	15.1
Changsha	765	22.2	666	18.6	635	15.2	632	15.5	0	0.0	1260	13.9
Guangzhou	532	15.4	433	12.1	346	8.3	326	8.0	419	15.1	1112	12.3
Kunming	0	0.0	0	0.0	724	17.4	678	16.7	664	23.9	1259	13.9
Yinchuan	525	15.2	598	16.7	592	14.2	658	16.2	0	0.0	1320	14.6
Income
<¥100	652	18.9	591	16.5	404	9.7	213	5.2	35	1.3	662	7.3
¥1000–¥2999	1548	44.8	1622	45.2	1609	38.6	1164	28.6	299	10.8	2644	29.2
¥3000–¥4999	668	19.4	746	20.8	1188	28.5	1257	30.9	666	24.0	2360	26.1
¥5000–¥6999	234	6.8	269	7.5	465	11.2	678	16.7	730	26.3	1439	15.9
¥7000–¥8999	57	1.7	61	1.7	134	3.2	298	7.3	338	12.2	578	6.4
¥9000 or above	59	1.7	71	2.0	135	3.2	284	7.0	491	17.7	771	8.5
Don’t know	234	6.8	226	6.3	237	5.7	176	4.3	216	7.8	593	6.6
Smoking status
Daily	3250	94.2	3420	95.4	3996	95.8	3863	94.9	2627	94.7	8533	94.3
Weekly	202	5.9	166	4.6	176	4.2	206	5.1	148	5.3	513	5.7
Cohort
Recruited in Wave 1	3452	100.0	2943	82.1	2302	55.2	1524	37.4	737	26.6	4336	47.9
Recruited in Wave 2	–	–	643	17.9	476	11.4	251	6.2	130	4.7	784	8.7
Recruited in Wave 3	–	–	–	–	1394	33.4	789	19.4	448	16.1	1516	16.8
Recruited in Wave 4	–	–	–	–	–	–	1506	37.0	665	24.0	1616	17.9
Recruited in Wave 5	–	–	–	–	–	–	–	–	795	28.7	795	8.8