Probabilities of detecting frequency differences based on data obtained by random sampling were determined by computer simulation. Artificial, monotypic populations of known frequency were generated and sampled. Sample sizes of 100, 200, 500, and 1,000 plots were used to compare baseline populations of 20, 50, and 80% frequency to populations having progressively larger or smaller frequencies. Probabilities of detecting a difference in frequency from baseline populations were empirically estimated from 10,000 comparisons using a test of proportions (P<0.05). Results indicated that the power of the test was substantially reduced at lower sample sizes. Equating the probability of Type I and Type II errors at 0.05 resulted in sample sizes of approximately 500 plots being needed to statistically distinguish between differences of plus or minus 10% frequency. This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.