Proportional Mortality Indicator (PMI) is defined as percentage of deaths at the ages 50 years-old and over to the total deaths in a population. This is essentially an indicator of age-distribution of deaths. Nevertheless, it reflects the levels of health of the population in developing countries sensitively. However, there have been no way to link such an indicator of age-distribution of deaths with other mortality indicators based on age-specific death rates such as life expectancy at birth. In this paper, the author tried to find out the missing link between these two types of mortality indicators. Considering that the values of l(x) function of a life table correspond to the proportions of deaths at the ages x year-old and above in the life table population, the author examined the relationships between the values of l(x) at various ages and life expectancy at birth. Using 90 pairs of reliable male/female empirical life tables representing a wide variety of mortality schedules in human populations, the values of l(x) at the ages 50 to 60 were shown to have very strong linear relationship between life expectancy at birth. The coefficients of correlation were as high as 0.99, even when male and female life tables were pooled together. The results were also shown to be in agreement with the life table theory which is known as Brass logit system. Based on these results and considering the effect of aging of population which follows a demographic transition, a theoretical interpretation of levels of PMI in actual populations was proposed.

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In accordance with the transition from a high-growth economy to a slow-growth economy, not only the volume but also the pattern of internal migration in Japan shows a drastic change. During the rapid economic growth period from the latter half of the 1950s to an early part of the 1970s, the number of migrants to metropolitan areas from other areas increased continuously. During the slow economic growth period from an early part of the 1970s to the present, however, the volume of internal migration has been decreasing mainly because of the decline in the number of in-migrants to metropolitan areas. Together with the performance of economic growth, the dynamic structural and geographical transformation in postwar Japanese economy also has affected the changes in internal migration. Based on the economic indicators such as net prefectural products by industrial origin, prefectural income per person and number of increase in persons employed, it is indicated that regional economic differentials have been smaller through the achievement of high economic growth. This reduction of regional economic differentials has a big effect on the mobility decline. Considering the trends of interprefectural migration and of economic activities in each prefecture, it may be hypothesized that during the high economic growth period, the increase of job opportunities in secondary industry had the strongest influence on interprefectural migration among industries but after the shift to the slow economic growth period, its power to the migration has weakened and been replaced by the increase of job opportunities in tertiary industry. To consider the future prospects of internal migration in Japan, thus, one should pay close attention to a trend of activities in tertiary industry.

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Ever since 1960, most of the remote mountain villages in Japan has experienced heavy out-flow of native junior and senior high school graduates, and young farmers. Furthermore, growing number of farm families has moved to city regions. Population and households of the remote villages diminished severely. As a result, many difficulties arose both in industrial activities and in daily life of the region. We call it "KASO problem" in the gross. The "KASO region" contains all the communities suffering from this "KASO problem". From about 1965, the national and local government authorities grasped the severeness of "KASO problem". They have planned and introduced many counter-measures to mitigate and conquer those problems. After twenty years of efforts, has "KASO problem" improved much better? How is the present status of KASO regions? I examined in this paper these two subjects chiefly from demographic viewpoint. According to the White Paper on KASO (that is the yearly governmental publication explaining the status of KASO regions and governmental counter-measures), total population of KASO regions decreased from 12,75 million of 1960 to 8.17 million of 1985. But now the heavy out migration in the 1960's has almost calmed. The intercensal population decrease was more than 10% in the 1960's, But, in the 1980-85 period it fell off to 3%. The number of local communities that experienced population diminution of 10% and above decreased from 877 in the 1965-70 period to 107 in the 1980-85. However, the population decrease of KASO regions has never stopped. The heavy out-flow of youngsters continues even now. As the resultant severe aging of population, the rise of death rate will become remarkable. The result of population projection shows that the rate of population decrease will rise to the double in the 2005 year. At present, the most serious social problem in KASO regions is a rapid increase in the number and the proportion of population aged 65 and above. The proportion reached 17% in 1985 (as for national population, it is 10.3%), and the speed of aging process will become much faster. In 2005 the proportion will augment to 27.5%. Accompanied with aging, natural decrease of population will grow even larger, and the number of old aged couples and elderlies living alone will increase rapidly. The aging aggravates the social welfare, but the more serious problem is its negative effects on the growth of local economy. In the 1970's, local economy has showed a marked development. The first basis of the growth was the abundance of native upper midde and old age population. Most of them were owner farmers. They worked on their own farm, and most of them had a side job. Their industriousness has worked as a driving force of the enlargement of local economy in the 1970's. But, most of them will be compelled to retire altogether from their jobs in the near future. Therefore, the source of supply of cheap and efficient labor in the local economy will dry up. Such a cursed process will cause maximal damage to the economy of KASO regions. The revitallization of local industry and community life in KASO regions now is the most difficult problem to the regional policy of Japan.

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