A series of successive administrations of a given instrument to a panel. At least two rounds are used in the Delphi technique to solicit forecasts from experts. Each round leads to improved accuracy, although with diminishing marginal returns. Rounds are expected to be especially useful when the panel is small (say about five), when misinterpretations are likely, the problem is difficult, and the experts are heterogeneous. (See Rowe and Wright 2001.)