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Arguments - Prediction Error

While the general trends of the change in diet seem rather predictable in China, the specific diet pattern is not. Moreover, it is the specific diet pattern that can greatly affect overall grain demand. In the case of China, diet may be more important for the overall food demand than population growth.

Crucial Issues
Can we predict diet change? Let us focus on two issues:
WB00860_.gif (262 bytes) The background: Why is it difficult to predict diet change?
WB00860_.gif (262 bytes) What methods are available to predit diet change?
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Background: Why is it difficult to predict diet change?
Predicting diet change in China does not seem too difficult, because the range of possible change is limited and most of the change has probably already occurred. For any further change, there are only two likely possibilities. If the country follows its current path of economic reform and development, its diet will most likely become similar to those of other developed Asian countries. It will become more diverse, it will probably include more animal products (milk, fat), and it will have a higher percentage of foods with high sugar content, such as sweet beverages, ice cream, and cakes. People will also drink more alcohol. However, if economic crises strike or if a return to command-and-control agriculture should occur, China would probably change back to the staple diet of rice, wheat, and tubers that was typical in the 1950s and 1960s. While these two general scenarios seem obvious, many uncertainties exist in the details. Will Chinese consumers in the future prefer pork or poultry, freshwater fish or sea fish? How much will consumption of milk products increase? How much will consumption of alcoholic beverages and stimulants increase?
In our in-depth analysis, we have tried to model China's future food demand as it depends on diet change and other factors. The bottom line of this analysis is that diet matters. In fact, in the case of China diet change could have a bigger impact on overall food demand than population growth (for details, see the in-depth analysis). The analysis shows that overall food demand could vary considerably depending on the specific diet pattern (see Table 1).
Projecting China's food demand in 2025 and 2050

China's Food Balance in 1964-66
Table 1
What methods are available to predict diet change
The simplest method for predicting change in diet is to extrapolate current trends. Unfortunately, this method produces unrealistic results if applied to more than a few years. For instance, if we extrapolate China’s steep per capita increase in meat consumption for the next 30 years, we get a completely meat-based diet by the end of the projection period. Obviously, diets can change only in a relatively narrow range: it is unlikely that China’s population would eat, on average, more than 60 or 70 kg of meat per person per year.
Alternatively, we can use the current food consumption patterns of other, already developed Asian countries as a target pattern for China. One can imagine that China’s average diet will approach the current pattern of Hong Kong, Singapore, or South Korea. However, there are deep ethnic and cultural differences between countries that must also be taken into account.
Finally, we can develop a model of change in diet that predicts food consumption patterns from related social and economic factors. For instance, we could calculate the elasticity of meat consumption by income or level of urbanization. With growing income or urbanization, consumption of meat would increase. Unfortunately, the income elasticity for most food items is already low in China. For instance, an income increase would not greatly affect average meat consumption in China, because it is already very high and the small marginal increase from income growth would not make a big difference. Income growth was certainly important for China's change in diet over the past few years, but in the future, food preferences will depend more on changes in lifestyle (which are hard to predict) than on income.
Related Arguments

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.)