Effect of Spatial Distribution on Determining the Number of Samples Required to Estimate Populations of Hypera postica, Sitona hispidulus , and Hypera punctata1 for Specified Probability and Accuracy Levels 2
- 1 April 1982
- journal article
- research article
- Published by Oxford University Press (OUP) in Environmental Entomology
- Vol. 11 (2) , 444-451
- https://doi.org/10.1093/ee/11.2.444
Abstract
Sample size (required number of sample units), with specific consideration for spatial distribution and a dispersion parameter, was determined for adult Hypera postica sampled by 1-ft 2 (929-cm 2 ) alfalfa quadrats, and Hypera postica, Sitona hispidulus , and Hypera punctata adults sampled oy 1-ft 2 emergence traps in wood edge aestivation sites. Taylor's power law ( s2 = am b ), and the sample size equation N = (100/ c ) 2 t 2amb−2 provide an efficient means for this determination. Sample size-density estimate curves are presented for four probability (confidence) and three accuracy (precision) levels. Sample size was inversely proportional to adult weevil density in all cases except for S. hispidulus , where the sample size was directly proportional to density. At the 95% probability and 20% accuracy levels 1,173 quadrats are required to estimate an adult H. postica density of 0.1. A 40% accuracy level with this same probability level will estimate densities of H. postica as low as 0.3 per quadrat with only 100 samples.This publication has 1 reference indexed in Scilit:
- Optimum Sample Size and Comments on Some Published FormulaeBulletin of the Entomological Society of America, 1976