Differential piece-rate by Taylor uses two rates because:

1. Taylor's differential piece-rate uses a low rate below standard and a high rate at or above standard. 2. The intent is to penalise below-standard performance and reward above-standard performance. 3. Workers therefore have a strong incentive to meet or exceed the standard. 4. Hence the answer is to penalise below-standard workers. _Source: ICAI BoS Inter Paper 3, Ch 3 "Employee Cost", §3.8.3 ¶2_