"The ITRA Performance index (PI) is a tool to evaluate the performance level of trail runners, based on their speed."
"The general PI is calculated using a weighted mean of the 5 best Race Score obtained on a race regardless of the distance category, over the previous 36 months."
"The distance category PI is calculated using a weighted mean of the 5 best Race Score obtained under one same distance category, over the previous 36 months."
Runners can obtain a PI after finishing at least 1 ITRA race but its best accuracy is reached after finishing 5 races.