Arguments - Data Quality
|The statistics on
meat consumption in China necessary to calculate China's (future) food demand are
sufficiently reliable. There are some inconsistencies between (official) meat production
statistics and data on per capita meat consumption from household surveys. However, the
overall trend is clear. All statistics indicate that the consumption of meat has increased
significantly in both urban and rural areas; the only discrepancy lies in the amount of
assessing the quality of statistics on change in diet, two questions are crucial:
||What data sources are
available to analyze change in diet in China?
||How reliable are the
|What data sources are available?
three major sources of (statistical) information on diet change in China. First, we can
analyze agricultural production statistics by commodity, such as the harvested amount of
wheat, rice, vegetables, fruits, or meat. These statistics are readily available from the
Chinese Statistical Yearbook, and they can give us a good idea of the trends in China's
Second, we can analyze data from Chinese household surveys. They include information on
the amount of certain food items actually available on average for consumption.
Finally, we can use so-called food balance sheets, which not only provide domestic
production statistics for the major primary commodities, but also quantify the (domestic)
utilization of these commodities within a food system. For instance, for each commodity,
they take into account the amount of feed, waste, and industrial processing, all of which
reduce the amount that is available for direct human consumption. These food balance
sheets have the great advantage that by definition they balance all sources of supply with
all utilization of the commodities.
|How reliable are the data?
data for various agricultural commodities, such as rice, wheat, or meat, are probably
quite reliable in China. However, these statistics do not indicate what amounts of various
commodities are actually available for human consumption. They do not include net imports
of these commodities, and they do not take into account all uses of the commodities -
including their use as seeds, as animal feed, and as products for non-food processing, in
addition to their use for direct human consumption.
surveys should provide the most accurate representation of China's food supply. There are,
however, some methodological problems: household consumption statistics require that
household members provide a detailed, complete, and accurate account of the foods they
have consumed during a certain period, both at home and in restaurants. It is doubtful
that all the households interviewed are able to provide this information. With this in
mind, it is not surprising that available food consumption statistics based on Chinese
household surveys are somewhat inconsistent with official production data.
food balance sheets should take into account the complete food chain, from the field to
supply in the shops. They are an accounting scheme that balances, for each agricultural
commodity, production, exports, imports, overall domestic supply, use as feed or seeds,
waste, inventory change, and direct use for human consumption. The FAO has developed food
balance sheets for all countries in the world. The data have been available from the
FAOSTAT system since the early 1960s. The balances are based on official data reported by
the countries. The FAO extensively cross-checks these data and makes adjustments where
necessary, so the food balance sheets are usually considered to be quite accurate.
Ideally, the FAO food balance sheet on China should provide a complete macrodescription of
the national food system. However, the balance sheets can be only as good as the primary
statistical information. Unfortunately, these detailed statistical data - especially
information on the amount of waste - are not always available for all commodities. Missing
data have to be estimated so that the sheet can be balanced. Such estimations inevitably
introduce inaccuracies. Moreover, food balance sheets only describe the overall national
supply; they do not take into account regional variations, which are probably substantial.
Another disadvantage of food balance sheets is that they only provide data for the
domestic food supply. They do not indicate how much of this overall supply
actually reaches the consumer. They also cannot distinguish the supply of urban and rural,
or poor and rich households.
cross-check the various sources of statistical information on food consumption in China,
some inconsistencies become obvious. For instance, if we multiply per capita meat
consumption from the household surveys by the population size, we do not get a total meat
consumption that matches the total domestic supply (see Table 1). These inconsistencies
might be caused by incorrect responses to the survey, by a sample that is not
representative of the whole population, by differences in commodity classification, or by
incorrect production statistics. However, despite these inconsistencies, it is obvious
that all available data point toward a significant change in diet in China.
Diet Change: Trends
Impact Data Quality Prediction Error Intervention Possibilities Intervention Costs
Revision 2.0 (First revision published in 1999)
- Copyright © 2011 by Gerhard K. Heilig. All rights reserved. (First revision: Copyright © 1999 by IIASA.)