No abstract

Background Social contact surveys can greatly help in quantifying the heterogeneous patterns of infectious disease transmission. The present study aimed to conduct a contact survey in Japan, offering estimates of contact by age and location and validating a social contact matrix using a seroepidemiological dataset of influenza. Methods An internet-based questionnaire survey was conducted, covering all 47 prefectures in Japan and including a total of 1476 households. The social contact matrix was quantified assuming reciprocity and using the maximum likelihood method. By imposing several parametric assumptions for the next-generation matrix, the empirical seroepidemiological data of influenza A (H1N1) 2009 was analysed and we estimated the basic reproduction number, R 0 . Results In total, the reported number of contacts on weekdays was 10,682 whereas that on weekend days was 8867. Strong age-dependent assortativity was identified. Forty percent of weekday contacts took place at schools or workplaces, but that declined to 14% on weekends. Accounting for the age-dependent heterogeneity with the known social contact matrix, the minimum value of the Akaike information criterion was obtained and R 0 was estimated at 1.45 (95% confidence interval: 1.42, 1.49). Conclusions Survey datasets will be useful for parameterizing the heterogeneous transmission model of various directly transmitted infectious diseases in Japan. Age-dependent assortativity, especially among children, along with numerous contacts in school settings on weekdays implies the potential effectiveness of school closure. Electronic supplementary material The online version of this article (10.1186/s12976-019-0102-8) contains supplementary material, which is available to authorized users.

We present empirical evidence on gender differences in wage returns on firmspecific experience (job tenure) and general experience. We find that overall returns on an extra year of labor market experience are lower for women than men. However, a decomposition analysis shows that the return on job tenure is substantially lower for women than it is for men, and that the return on general experience is higher for women than it is for men. These findings are consistent with the hypothesis that despite their growing attachment to the labor market, women are less likely to invest in job-specific skills or to self-select into jobs with backloaded compensation because women are more prone to job separations than their male counterparts. The lower estimated returns on tenure for women could also be due to employer discrimination in hiring, and the provision of training and promotion opportunities within firms.