Keio Research Highlights

Karoushi is a Japanese word that means 'death by overwork'. In a country notorious for its long working hours and tradition of lifetime commitment to a single company, this term is familiar to many. Isamu Yamamoto at the Faculty of Business and Commerce, Keio University, has been studying this characteristically Japanese work culture for the last seven years with the aim of identifying some of its underlying motivations and effects on productivity.

Yamamoto developed an interest in the subject prior to joining Keio University during his years of working at a quintessential Japanese company ― a Japanese bank. He explains, "That is where I found my research question: Why did so many of my colleagues regularly work very long hours every day?"

By analyzing the allocation of human resources and examining the relationship between work-life balance and the mental health and performance of workers, Yamamoto hopes to contribute to the development of better labor systems in Japan.

His research makes extensive use of government statistics and census data, but also involves surveying hundreds of workers and firms over time, a type of longitudinal data called panel data ― an area where Yamamoto is assisted by Keio University's Panel Data Research Center.

Using a unique data set on managerial-level employees who were transferred from Japanese to European branches of the same global firms, Yamamoto found that the daily hours worked by Japanese workers dropped significantly when they were relocated to European offices that did not have a long working-hour culture¹. This finding shows that Japanese workers are no more inclined to work long hours than workers in other countries, but are instead influenced primarily by the work habits of their peers.

Using another data set for Japanese male workers and their matched firms he also discovered that long hours is a product of a rational strategy by Japanese companies to maintain a skilled workforce². Companies value and honor the lifetime commitment and skill accumulation of their employees, and to avoid the need for layoffs during downturns, they tend to understaff, resulting in chronic overwork of incumbents ― the downside of lifetime employment.

Yet with long hours comes an inevitable drop in human productivity. "Japanese employees are now working so long that the labor productivity is among the lowest of the developed countries," notes Yamamoto. He hopes that his team's research will one day lead to these issues being addressed at the level of national policy.

1. Kuroda, S. & Yamamoto, I. Do peers affect determination of work hours? Evidence based on unique employee data from global Japanese firms in Europe. Journal of Labor Research 34, 359-388 (2013). | article
2. Kuroda, S. & Yamamoto, I. Firms' demand for work hours: Evidence from matched firm-worker data in Japan. Journal of the Japanese and International Economies 29, 57-73 (2013). | article