The name is absent

H. Mori et al. /International Food and Agribusiness Management Review 3 (2000) 189-205

Table 3

Standard cohort table—a hypothetical case of certain food intakes by age groups, 1970, 1980 and 1990

ings, however. The inherent assumption is that each member of the household is the same age
which may be true only in the case of households consisting of a same-age couple only.

A model to more accurately derive individual consumption was developed by Mori and
Inaba (1997). The model makes use of household composition estimates. The use of this
method has solved, if not without weakness, the problem of individual consumption deri-
vation. The resulting data contains per capita consumption estimates of household members
by age group for individual commodities.

With data available in this form over time, it is possible to estimate age, period, and cohort
effects. Period effects are those influences attributed to the time period of the survey, such
as changes in income, prices or trade policy, or food-borne disease outbreaks. Age effects are
those effects associated with physical and mental aging. Over the life cycle, nutritional
requirements change, as do tastes and preferences. Cohort effects are those influences
attributed to a particular birth cohort. These include major events or shifts in social attitudes
that shape tastes and preferences for particular foods.

A cohort table has survey period on one axis, and age groups on the other. If the survey
period is every 10 years, then defining age groups with 10-year intervals will create a
“standard cohort table” (Table 3). A “general cohort table” is one in which the range of the
age groups does not necessarily correspond with survey periods.

Exact evaluation of a cohort table is not as easy as it may look. For example, consider the
diagonal line labeled as (1) in Table 3. The 20-29 year-old group in 1970 and the 30-39
year-old group in 1980 belong to the same (birth) cohort, born during the 1940s. Their
consumption increased from 10 to 17 kg from 1970 to 1980. The difference of 7 kg can be
attributed to two factors, aging effects from twenties to thirties and period effects from 1970
to 1980 which are combined and not readily identifiable.

The 30 -39 year-old group and 40-49 year-old group consumed 17 and 20 kg,
respectively, in 1980 (the horizontal line (2)). The difference of 3 kg cannot be explained
by the age factor alone, since the latter age groups belong to the different cohort, born
during the 1930s. Here again, the composite effects of age and cohort are not easy to
separate.

Lastly, the 30 -39 year-old group consumed 17 and 14 kg in 1980 and 1990, respectively
[vertical line (3)]. The difference of 3 kg in this case cannot be ascribed to the passing of time

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