The authors make a correction of aggregation by calculating weightings in terms of amounts actually invested (discounted value of payments made by investors), which makes the aggregation of the profitability indexes
Novices and experts will find much here; from financial fitness evaluators and profitability indexes
to setting target prices for buy and sell ratios.
The benefit of calculating profitability indexes
is that the higher the PI of an investment, the greater its return per dollar invested.