Expected value of partial perfect information (EVPPI)

The expected value of partial perfect information (EVPPI) represents the maximum price a healthcare decision maker would (in theory) be willing to spend to gain perfect information for at least one uncertain parameter (input) in an economic model. EVPPI is calculated as the difference in the monetary value of the optimal decision under current uncertainty versus the expected value of the optimal decision if perfect information were available for only the selected subset of parameters. Closely related to EVPI (expected value of perfect information) and EVSI (expected value of sample information), EVPPI is primarily used to assess the value of conducting further research (e.g. expensive trials, registries or other observational studies) to reduce specific uncertainties and inform better decision making.