Shingo Tatsumichi,Motohiro Morishima （2007), "Seikashugi from an Employee Perspective" , JAPAN LABOR REVIEW, VOL.4, NO.2, 79-104.
We must then ask ourselves if the introduction of Seikashugi has caused a
rise in systematic and operational differentials. Using the JILPT corporate
survey, it is clear by looking at the results of the multiple regression analysis
where the controls were industry and size that both systematic and operational
differentials are higher in companies that had introduced Seikashugi than in
those that had not. Statistical analysis also confirms the accuracy of the general
opinion that “Seikashugi increases the wage differential.”12
