Data Collection
Household Survey
Detailed demographic, economic, time use, labor force participation, asset ownership, and expenditure data have been obtained. Income can be approximated from the survey in three ways: through responses to direct questions about income, the summation of net receipts from all reported activities, and responses to questions about expenditures. Full income from market and nonmarket activities can be imputed. This detailed estimation of income represents a significant advance in the measurement of income in China. Inclusion of nonmonetary government subsidies, such as state-subsidized housing, is an especially important advance. In the health section, details about insurance coverage, availability of medical facilities, curative care and illness information with associated time and money costs, preventive care with a focus on immunizations, and use of family planning and other preventive services have been obtained.
Health and Nutrition Survey
All household members in 1991 and subsequent surveys provided individual data on dietary intake, body composition, blood pressure, health history, and health-related behaviors (e.g., smoking, beverage consumption, medication, key chronic diseases). These data include dietary intake for three consecutive days as well as detailed physical examinations that include blood pressure (for adults); clinical measures of health; and measurement of weight, height, arm circumference, and head circumference (and waist-hip ratios beginning in 1993).
The three consecutive days during which detailed household food consumption data have been collected were randomly allocated from Monday to Sunday and are almost equally balanced across the seven days of the week for each sampling unit. Household food consumption has determined by examining changes in inventory from the beginning to the end of each day, in combination with a weighing and measuring technique. Chinese balances with a maximum limit of 15 kilograms and a minimum of 20 grams have been used. All processed foods (including edible oils and salt) remaining after the last meal before initiation of the survey have been weighed and recorded. All purchases, home production, and processed snack foods have been recorded. Whenever foods have been brought into the household unit, they have been weighed, and preparation waste (e.g., spoiled rice, discarded cooked meals fed to pets or animals) has been estimated when weighing was not possible. At the end of the survey, all remaining foods have been again weighed and recorded. The number of household members and visitors has been recorded at each meal.
Individual dietary intake for the same three consecutive days has been surveyed for all children age 1 to 6 and all adults age 20 to 45 in 1989 and for all individuals in later years. This step has been achieved by asking individuals each day to report all food consumed away from home on a 24-hour recall basis, and the same daily interview has been used to collect at-home individual consumption. In a few cases, subjects have missed one day because of absence, but over 99 percent of the sample has been available for the full three days of data.
The collection of both household and individual dietary intake allowed us to check the quality of data collection by comparing the two. Thus, each individual's average daily dietary intake, calculated from the household survey, has been compared with his or her dietary intake based on 24-hour recall data. Where significant discrepancies were found, the household and the individual in question were revisited and asked about their food consumption to resolve these discrepancies.
All field workers have been trained nutritionists who are otherwise professionally engaged in nutrition work in their own counties and who have participated in other national surveys. Almost all interviewers have been graduates of post-secondary schools; many have had four-year degrees. In addition, three days of specific training in the collection of dietary data have been provided for this survey.
The 1991 Food Composition Table (FCT) for China was utilized to calculate nutrient values for the dietary data of 2000 and previous years. This FCT represents a significant advance over the earlier China FCT both for higher quality chemical analyses and for improved techniques of developing average nutrient values for foods whose nutrient value varies over the country in a geographic context. The UNC-CH group has worked with the National Institute of Nutrition and Food Safety to update and improve this FCT. A newer version of FCT (2002) was used for the 2004 survey and the latest version (2004) was used for the 2006 survey.
Physical Activity
Child
We have used two methods to collect physical activity and inactivity data from our respondent children beginning in 1997. The first is based on questionnaires that collect reports of usual time spent in activities common in each of four settings. Activity questionnaires were designed by Barry Popkin and Barbara Ainsworth. Ainsworth was also involved in the design and evaluation of the activity questions for the U.S. Health Interview Surveys (HIS), the MONICA Optional Study of Physical Activity (MOSPA), and more recently the new International Physical Activity questionnaire for the World Health Organization. We expanded on the U.S. HIS questions to capture activity and inactivity measures, including TV viewing and other sedentary activities such as using computers, playing board games, and reading. Activities in and out of school, as well as culture-specific activity at home have been included.
The second method involves measuring of motion in a 24-hour period using the Caltrac Actometer. A subset of Chinese children provided these data. The Caltrac is a low-cost device that looks like a beeper and is attached to the waist. It registers motion in two dimensions and gives an estimate of total energy expenditure. The Caltrac was selected because it provides reasonably reliable and valid estimates of total activity, is cost effective, is feasible for use in a variety of field settings, is non-invasive, and is well-accepted by children. Questions on sleeping time and the nature of days for the child were also asked in conjunction with the Caltrac data. However, this practice was discontinued in 2004.
Adult
A small set of questions about the nature of occupation work has been included since 1997 to capture some energy-expenditure-related dimensions of each adult's work. The questions addressed physical activity involved in work and have complemented a set of energy-expenditure questions that had been asked as part of the nutrition data collection for all adults since 1989.
The Elderly Component
Since the 1997 survey, we have collected a full series of questions on activities of daily living and instrumental activities of daily living along with a shorter set of cognition questions. Drs. Robert Wallace and Namvar Zohoori developed these in Beijing in collaboration with the Chinese group. Wallace, who was responsible for the health component of the National Health and Retirement Survey in the U.S., and Zohoori began with a comparable set of questions and adjusted them to fit the Chinese culture. Additional questions have been added on time use for the care of older persons living inside and outside the home, and inter-generational transfers from children to their parents and vice versa. The CHNS has obtained data quite similar to that collected by the National Health and Retirement Survey now for many dimensions of elderly behavior.
For CHNS93 and all subsequent surveys, we have developed and added questionnaire components on activities of daily living (ADL) and intergenerational transfers from adult children to their older parents and vice versa. With the exception of some adaptation to the Chinese situation, the ADL survey was designed to be comparable with the Health and Retirement Survey and other U.S.-based National Center of Health Statistics surveys. This section was considerably refined based on the state of art at the time of the survey and on the pretests undertaken in China. We collected not only the standard ADL data but also have implemented an independent approach termed the PULSES approach.
The PULSES score is less sensitive for the elderly than for other groups, so it can be used only in an elementary way for checking the predictive ability of the ADL measures. The PULSES score taps a wider dimension than physical functioning but provides much less detail on each item. Other approaches were used to check the predictive validity of the ADL data. Internal consistency and observer consistency (inter- and intra-observer) studies have been undertaken.
In addition, CHNS93 enlarged the depth and range of measures of help received by household members as well as parallel measures of help given by household members. Questions have dealt with caregiving and access to resources and commodities, including foreign cigarettes or appliances, help in getting special foods needed to treat a variety of illnesses, and help in figuring out how to find the best doctor when someone is ill. For each household member, information about the source of assistance has included age, gender, relation to respondent (including living in the household or not and, if not, whether previously resided in the household and whether the helper was a relative, school classmate, work friend, or neighbor), occupation, and political status (party member, cadre). Similar information has been collected about care recipients from household members. Since a good deal of caregiving information had already been collected, our task was to fill in all the missing pieces so that complete and consistent information was gathered for all household members.
The CHNS data are part of a broader initiative to create modules sensitive to questions of aging. Many of the measures described in this section have been part of what is termed inter-generational transfers. The typical and most important categories are the transfer of money between elderly family members (who may or may not be members of the sample household) and the exchange of food, clothing, and child care/elder care.
Body Image and Mass Media Behaviors and Practices
In 2000 and later surveys, body images were created to match Chinese body types. All children age 6 through 18 have been asked about their desired body type and actual body type using card shuffle techniques. These questions were developed by Jane Brown and Peggy Bentley with the help of Penny Gordon-Larsen, all UNC faculty working in this area. In addition, each child was asked a selected set of questions related to the mass media. Mothers were asked a series of questions about mass media and television related to the children. These questions were included in the Ever-Married Women questionnaire for women with a child age 6 through 18.
Ever-Married Women Survey
Information from all ever-married women under age 52 has been collected beginning in 1991. The questions were revised and expanded in 1993. These data have included complex marriage and fertility histories and additional information was also collected on family planning, pregnancies, and infant feeding during inter-survey intervals.
Community Survey
The community questionnaire (filled out for each of the primary sampling units) has collected information from a knowledgeable respondent on community infrastructure (water, transport, electricity, communications, and so on), services (family planning, health facilities, retail outlets), population, prevailing wages, and related variables.
Food Market Survey
In the first two CHNS surveys, state and free market data were collected. But by 1997 none of the communities had separate state prices, so only free market stores and large stores have been visited. In all cases prices have been collected for a representative basket of commodities.
Health and Family Planning Facility Surveys
In 1989, 1991, and 1993, separate visits were made to obtain in-depth data in each community for every identified health service and family planning provider or facility. Information was collected concerning personnel, sources of funds, services available, prices (asked separately for insured and self-pay patients), and distance to the primary sampling units served by the facility. A separate questionnaire was administered to the local family planning official about family planning policies in the community. These sections were discontinued in 1997, but selected questions asked of these same personnel as part of the community questionnaire.