Number 08/Networks & contagion/Policy
The Displacement Ratio
The quantity
The ratio of pressure moved elsewhere to pressure removed at the intervention site. A value near one means the intervention relocated the problem rather than solving it.
01Why it matters
It is the single number that distinguishes protection from displacement, and it is almost never estimated before an intervention is declared successful.
02Expected value
Between 0.3 and 1.0 for area-based restrictions in open systems such as fisheries and land use.
03How it would be measured
Measure the target outcome inside and adjacent to the intervention area, before and after.
04What would refute it
A ratio near zero would mean displacement is negligible and the concern misplaced.