PND (percentage of non-overlapping data)

PND is the share of B values that exceed the best baseline value (Scruggs et al. 1987). With “lower = better” the lowest A value counts. Rule of thumb: above 90% very effective, 70 to 90% effective, 50 to 70% questionable, below that ineffective. PND is easy to understand but depends on one single baseline value: an outlier there makes PND useless.

Example: PND = 87%: 13 of 15 intervention values lie above the best baseline value.

Caution: PND depends on one extreme value and gets smaller with more measurements in A even if nothing else differs. NAP is therefore better suited as the main index; PND is shown for comparison with older work.