Designs for detecting trend from repeated surveys of ecological resources

We report investigations on trend detection capability (power for linear tr end) from repeated surveys of the same regional resource population. The te mporal sampling plans range from periodic revisits using panel designs to i ndependent surveys at each point in time; the latter have only random revis its. We view the resource of interest as a finite population but characteri ze several features of the situation with components of variance. The resul ts show how components of variance for site, year, and residual and samplin g fraction impact power to detect a specific trend. The panel designs turn out to be far superior to independent surveys for detecting trend and have other desirable features.