A polling of experts utilizing the following procedure:
- Select a group of experts (usually three or more).
- Solicit, in isolation, their independent estimates on the value of a particular parameter and reasons for the choice.
- Provide initial results to all experts and all revisions to initial estimates.
- Use the average of the final estimates as the best estimate of the parameter. Use the standard deviation of the estimates as a measure of uncertainty.
The procedure is interactive, with feedback between interactions.