The survey involved 16,616 households and was administered by the National Bureau of Statistics in 10 provinces: Beijing, Hebei, Heilongjiang, Zhejiang, Anhui, Henan, Guangdong, Sichuan, Yunnan and Gansu. All household members between 15 and 74 years old completed a 24-hour time diary for both a weekday and a weekend day in ten-minute intervals beginning at 4 a.m. Each individual also completed a personal questionnaire, which provides information including age, educational attainment, income level and occupation/employment status. The information on education, monthly individual income and the distance from home to office are expressed in categorical variables.