Why do economists use the midpoint method to calculate the price elasticity of demand between demand/price combination (q1, p1) and combination (q2, p2)?

You own a nonunion company with 93 nonexempt employees. all of these employ- ees pack books into boxes for shipment to customers throughout the united states. because of wide differences in performance, you have decided to try performance appraisal, something never done before. until now, you have given every worker the same size increase. now you want to measure performance and reward the best performers with bigger increases. without any further information, which of the five types of appraisal formats do you think would be most appropriate? justify your answer. do you anticipate any complaints, or other comments, from employees after you implement your new system?