Figure 1.

The moving average method shows that the operation time of both groups A and B decreased with increasing experience; and the first deflection was at around the 40th (47th in group A and 36th in group B) case.

The moving average method shows that the operation time of both groups A and B decreased with increasing experience; and the first deflection was at around the 40th (47th in group A and 36th in group B) case.