4. Results and discussions
4.1. Dynamic efficiency analysis
To examine the accuracy of the DSBM model, this study first compares the efficiency scores derived using the Banker et al. [73] (BCC) model and those obtained using the DSBM model. Table 4 summarizes the mean efficiency scores of sample life insurers from 2006 to 2010. Under the DSBM model, the results indicate that the range of average efficiency remained between 0.905 and 0.973 during this period. In contrast, the mean efficiency scores obtained using the BCC model decreased monotonically from 2006 to 2009 but increased in 2010. In fact, the mean efficiency scores obtained using the BCC model are consistently lower than those obtained using the DSBM model. The standard deviations under the DSBM model are generally lower than those under the BCC model. This suggests that considering carry-over activities could lead to more accurate efficiency estimation because the continuity of carry-overs from year to year is taken into account. In the life insurance business, life insurers cannot control their debt capital and equity over a short time period. Therefore, it is not practical to independently measure the performance of life insurers on an annual basis [21].