This article will refer to the Reactive Strength Index – Modified (RSImod) rather than the original Reactive Strength Index (RSI). The calculation for RSImod is jump height divided by time to takeoff in a countermovement jump. RSI refers to jump height divided by contact time in a drop jump.
The RSI Percentile Radar shows the Reactive Strength Index and the Peak Velocity of a Back Squat for a specific athlete compared to the rest of the team.