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various products over time by major age groups, but failed to identify pure period effects
with age and cohort effects compensated.
The main purpose of this paper is to measure effects of age, generation or cohort
membership, and period on changes in Japanese consumption of selected food items over the
past 20 years. In doing so quantitative guidelines will be generated for the more realistic and
dependable forecasts of future food demand in Japan. It is hoped that marketers, either
domestic or overseas, can use the information presented in this paper or to be further refined
to develop effective strategies geared to specific cohorts or current age classes.
2. What is a cohort?
A cohort is a group of people within a given population who experience a life event at
about the same time. The life event is one that shapes the group’s attitudes, preferences, or
lifestyles. Different cohort types include boom/depression, ethnic, education, or geographic
cohorts. The simplest and easiest cohort to track is the birth cohort. Those born within the
same time period tend to enter various stages of life at about the same time (Glenn, 1977).
It is important to distinguish between the terms “birth cohort” and “age groups.” An age
group includes people who are of a certain age at the time of the survey. This could be an
age group of people 65 to 69, say, retirement age. It is possible to compare the group’s
activities, savings or consumption of a particular product 20 years ago, with the same group’s
current activities. In doing so, note that the members of this group change, in age, from
survey period to survey period.
As the birth cohort moves through the life cycle, events shape the group’s preferences and
attitudes. The most profound is “coming of age.” This generally occurs between the ages of
17 and 21, or maybe slightly younger, or even older. The economic and social environment
at this time shape lifelong attitudes within the group. These are “formative years,” that will
have lasting, profound effects on the cohort group (Meredith & Schewe, 1994).
The population of the United States can be divided into birth cohort groups. For instance,
the depression cohort includes those born between 1912 and 1921. They were not born
during the Great Depression, but they entered adulthood between 1930 and 1939. It can be
hypothesized that devastating economic conditions during this time created a strong desire
to save and prepare for the future. The depression cohort is estimated to have maintained this
financially conservative behavior to the present day (Attanasio, 1997; Gokhale et al., 1996).
These habits are in stark contrast to those of the first boomer’s cohort. They were born
between around 1946 and 1954. When they came of age from 1963 to 1972, the nation was
experiencing good economic times. This group is marked by a desire to maintain the good
lifestyle they experienced while growing up. The assumption of large amounts of debt was
one way to do this.
In Japan, food was in short supply before, during and soon after World War II. Even in
1955, the year when the Japanese economy was said to have been restored to the prewar level
(Economic Planning Agency), most people depended on cereals for the important part of
caloric intakes and took very little animal protein, such as meat and dairy products. As the