The extent of direct and indirect effect of socio-economic factors on fertility in Japan was estimated with pathoanalysis. Path model was constructed based on ?gmodernization?h or ?gdevelopment?h theory which indicated economic development accompanying industrization and urbanization would accelate the reduction of fertility. The changing trend was speculated each five years from 1955 through 1980, therefore, six data sets which were aggregated by prefecture form the basis of analysis. From 1955 through 1965, industrization (=economic development) exerts the converse indirect effect on fertility through education factor in divergent manner during the period. In 1970 model, the selected variables failed to explain any contribution to fertility. Unknown factors are presumably involved. From 1975 through 1980, urbanization exerts the direct effect, and converse indirect effect through marriage rate on fertility. Industrization also carries the converse effect directly this period. I nfant mortality had played no substantial role during the whole period concerned. In consideration of marked change in 1970 model and the pattern has been hold thereafter, some renovation of behavior or consciousness might occur during the period between 1965 and 1975.
Subjects were 189 twin pairs, consisting of 165 MZ and 24 same-sexed DZ who entered the junior high school affiliated to Tokyo University (sample T), and 93 twin pairs, consisting of 71 MZ and 22 same-sexed DZ who were registered at Kinki University (sample K). The zygosity among them was previously identified by many genetic markers. This study aimed at the zygosity diagnosis by questionnaire. Questionnaire included threequestions. The first question was the similality of twins: "How are you alike?". The second was the frequency of being mistaken: "How often are you mistaken". And the third was to ask the person: "By whom are you mistaken?". According to the degree, 1-3 points, 1-3 points, and 1-4 points were given for each question. And the sum of the points of each pair of twins was calculated. Zygosity was determined by the sum of points, distributed from 6 to 20. Namely, if the sum is 6-13, we consider the twin pairs as MZ, and if the sum is 14-20, as DZ. It was revealed that more than 90% of twins were diagnosed correctly by use of this cutting point. And this result was in accordance with that obtained by use of discriminant function analysis. It was concluded that zygosity diagnosis by questionnaire was convenient and useful, in particular, for epidemiological research.
Based on the death records covering a 15-year period 1971 to 1985, the standardized mortality ratios (SMRs) for selected Cerebro-cardio-vascular diseases were calculated for each of 96 local community units (14 cities, 73 towns and 9 villages) in Kagoshima prefecture. These local communities characterized by the SMRs for different categories of cerebro-cardio-vascular disease were classified by the cluster analysis using the statistical package (Ward) on computer and the geographic difference in the characteristic of death rates from these diseases were explained by the ionic concentrations in local drinking water. Results obtained are as follows; 1) With a criterion of 7.5 in the cluster analysis, the 96 local communities were classified into five regional groups (Group I, II, III, IV and V), each of which could be regarded as the group of local communities with similar characteristics of SMRs for different categories of cerebro-cardio-vascular disease. A total of 33 local communities belonged to Group I, 16 to Group II, 25 to Group III, 11 to Group IV and 11 to Group V, respectively. All the local communities in Group IV were on the remote islands. 2) The values of SMRs for cerebrovascular disease in Groups I, II and III were higher than the expected level of 1 while those in Group IV and V were less than this level. For cerebral hemorrhage, the values of SMRs were higher than 2 in Group II, higher than 1 in Groups I, III and V and below 1 in Group IV. For cerebral infarction, the values of SMRs were higher than 1 in only Group III and less than 1 in the other Groups. For hypertensive disease, the values of SMRs were higher than 2 in Group V, higher than 1 in Group I, II and III, and less than 1 in Group IV. For ischemic heart disease, the values of SMRs were higher than 1 in only Group III and less than 1 in the other Groups. For other heart disease, the values of SMRs were higher than 1 in Groups I, II, III and V and less than 1 in only Group IV. Therefore, the values of SMRs for all of cerebro-cardio-vascular diseases were higher than l in Group III and less than 1 in Group IV . 3) On a Group basis, significant negative correlations were noted between SMRs of cerebrovascular disease and Mg, Ca, Mg + Ca or Ca/K in drinking water, between SMRs of ischemic heart disease and Mg or Mg + Ca, and between SMRs of other heart disease and Na, Mg, Ca, Cl or Mg +Ca. Similar negative correlations existed between SMRs of selected cerebro-cardio-vascular diseases and selected ionic concentrations, on a community basis for the 96 units. 4) Results of the multiple regression analyses showed that Ca and Ca-Na in drinking water were positively associated with deaths from cerebrovascular disease while Cl was negatively associated with that factor. They also showed that Na was negatively associated with deaths from cerebral hemorrhage, K was positively while Cl and Cl/K were negatively associated with deaths from cerebral infarction, Cl was negatively associated with deaths from hypertensive disease, Mg, Ca and Mg/Ca were negatively associated with deaths from ishemic heart disease, and Ca and Na were negatively associated with deaths from other heart disease, respectively.