Since 1955 we have reported the geographic variations of reproduction rates by prefectures in Japan. This report dealt with the results of the study for the years of 1975 and 1980. Method of estimating the number of births and female population by age was ameliorated and reported in detail in the separate report (Nanjo et al . 1987). In 1975 the prefectures where NRRs were kept above replacement level were 6, Okinawa, Nagasaki, Iwate, Fukushima, Miyazaki, and Shiga, and in 1980 only one, Okinawa. The highest NRR was observed in Okinawa for both 1975 and 1980, 1.4034 and 1.1340, and the lowest in Tokyo, 0.7763 and 0.6846 respectively. Geographic variations, which had changed due to the marked increments of NRRs in industrialized urban prefectures at the time of second baby-boom around 1970, have been returning to the former pattern of smaller NRRs in industrialized urban prefectures and larger ones in rural agricultural prefectures as observed in 1960. Distinct differences were noticed in age patterns of birth rates in different geographical area. Rural prefectures along the Japan Sea showed a pattern of higher rates in age 20's and lower rates after age 30's while prefectures having large cities with millions population showed the patterns of lower rates in 20's and higher rates after 30's. Age patterns of birth rates are closely related to the levels of NRR and prefectures with larger NRR have the former pattern, rural type, and those with smaller NRR the latter, urban type. The strong influence on NRR is now attributed to the fertility of age 20's rather than to the total fertility of ages from 15 to 49. Intrinsic vital rates were also calculated and given in the text .
The purpose of this study is a re-exmination of population dynamics, especially of marriage, divorce and legitimate and illegitimate birth, in Japan for the late 19th century. Although statistical data concerning population dynamics in Japan had been officially gathered since 1872, the few studies that analyze marriage, divorce and legitimate and illegitimate birth in the 19th century have been carried out. The marriage rates for the period between 1883 and 1898 were estimated at around eight per 1, 000 people. This figure is roughly the same as the marriage rates in the 20th century but other two indices related to the marriage rate were lower than those of the 20th century. The divorce rates for the corresponding period were estimated at three times higher than those of the 20th century . The birth rates for the period between 1872 and 1898 were estimated at around 30 per 1, 000 people and showed the increasing trend. But such increase was considered to be caused by the improvement of the registration system. For the same reason both the legitimate birth rates and the illegitimate birth rates showed the increase for the period between 1886 and 1898. But it is noteworthy that the ratio of illegitimate births to legitimate births had been elevating in those days.
Food consumption surveys of the female population were conducted every year in a semi-rural community for eight years. The authors examined their commitment to the surveys. The surveys have been executed on women's food consumption by weight record method every year since 1978 in Ohami-Shirasatocho, chiba prefecture. The results were as follows : 1) The population size was 108 in the first year, and it increased gradually to 196 persons in 1980. The number of the participants of the survey was between 80 and 106. The participation rate of the population was 74.1% in 1978 and 82.5% in 1979. It decreased gradually to 49.0% in 1985. 2) The participation rate showed decreasing tendency during the observed pariod with some fluctuation. Half of the participants in the first year remained in the survey in the last observed year. 3) Up to the fourth year, the rate of those who dropped out was over 60%. But, it became fewer after that year. About 24% of the original participants in the first year still remained as active participants in 1985, even after eight years. 4) The frequency of participation shows ; while the participants in 1978 were surveyed 7 or 8 times, those who began to participate in subsequent years were less active in the survey. 5) It is desirable to consider these factors at the planning stages of the field survey in order to maintain a certain number of participants.