The accepted definition of overshoot is a simultaneous reduction in both P ̅ and Ī when moving from low to high to low external resistance on a power density curve, i.e., when ΔP < 0 and ΔĪ < 0 occur between any consecutive data pairs in a power density curve. From Eqn. 5, it is sufficient to note that ΔĪ < 0 meets this definition because Δ P is then necessarily negative as well. Therefore, the simplest way to quantify overshoot is to measure the absolute overshoot with the parameter ΔĪOS (A), which is a positive value in the presence of overshoot: