## V I Household and migration

The household often functions as a unit of migration, and a household change is frequently accompanied by migration. The relationship between migration and household is an important issue for both household studies and migration research. Data on household migration can be obtained from the 1990 Population Census, but these lack information on reasons for migration so it is impossible to observe household migration from the viewpoint of the causes of move. This section analyzes household migration types not only by variables such as age of household head, family type of household, or residence of household head five years earlier, but also by household head's reason for migration.

## 1 Household by migration type

Household migrations are categorized here into the following three types. A household in which all the present members (excluding those who died or moved out in the past because their data are not collected) did not live in the present residence five years earlier is defined as a household with “all members moved.” If at least one of the present household members lived in the present residence five years earlier (regardless of his/her relational status in family), this household is called a “partly moved” household. Furthermore, a household where all the present members lived in the present residence five years earlier is defined as a “no move” household. To be precise, there are possibly some household members who repeatedly moved between the present residence and other places in the last five years. It is also possible that there are out-movers in “no move” households. But, since the Population Census uses a similar categorization of household migration (household with “all the related members that moved,” with “some related members who moved,” and with “no related members who moved”), the above grouping is used here. The number of “no move” households is 9,661, 68.6% of the total 14,083 households. The number of households with “all members moved” is 3,654, and that with “partly moved” is 670, accounting for 25.9% and 4.8% of the total, respectively (Table 17).

Table 17 Households by migration type (for the period 1991-1996)

Total	All members moved	Partly moved	No move	Unknown
Total households	14,083	3,654	670	9,661	98
Percentage (\%)	100.0	25.9	4.8	68.6	0.7

## 2 Migration type of household by age of household head

Distribution of household migration types by age of household head shows that the percentage of “all members moved” is high among households with young heads. As the head’s age rises, this percentage decreases. Up to the 30-34 age group, for example, the percentage is approximately between 60-95%. But, it becomes less than 50% after 35 years of age. In the 60-64 and over age group, it is about 5%. This tendency is basically the same even if we add the percentages for “partly moved” to that of “all members moved.” As the head’s age rises, the total percentage of “all members moved” and “partly moved” decreases. In the 35-39 age group, it declines below the 50% level. It decreases to approximately 10% in the 65-69 and over age group. On the other hand, the percentage of “no moved” becomes larger in higher age groups. It surpasses 50% in the 35-39 age group, and reaches about 90% in the 65-69 and over age group.

In sum, the percentage of “all members moved” is higher in households with younger heads. As the head’s age rises, the percentage of “no move” increases. This tendency seems to be related to the fact that households with young heads are in the phase of household formation, and that many of these household