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A Statistical Method for Determining Quadrat Size and Adequacy of Sampling
Author(s) -
Rice Elroy L.
Publication year - 1967
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934565
Subject(s) - quadrat , statistics , sample size determination , sampling (signal processing) , mathematics , confidence interval , sample (material) , standard error , ecology , computer science , biology , chemistry , filter (signal processing) , shrub , chromatography , computer vision
A procedure is suggested to eliminate dependency on the species—area curve, based on the view that the most important fact of plant distribution is the distribution of quantity of material as indicated by cover, either areal (projective) or basal area. The first step in the procedure (applicable to density data also) is to determine the proper quadrat size to give a reasonably normal distribution of the desired data for the various species for which quantitative results are desired. The next step would be to determine how many quadrats of the determined size would be necessary to give reproducible data. It is suggested that the most satisfactory procedure to determine adequacy of sampling would be to obtain confidence limits for the mean from the sample estimates of the mean and standard error. If it is decided that the confidence interval for the mean based on a given number of qudrats is too broad, a larger sample is indicated.