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Angular transformation – another effect of different sample sizes
Author(s) -
KASUYA Eiiti
Publication year - 2004
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1111/j.1440-1703.2003.00620.x
Subject(s) - transformation (genetics) , mathematics , statistics , sample size determination , sample (material) , overdispersion , value (mathematics) , mean value , biology , physics , count data , biochemistry , gene , poisson distribution , thermodynamics
Angular transformation has been widely used to analyze proportions or percentages in ecology. A new type of artifact can arise by applying angular transformation to proportions or percentages. Proportions with the same mean or expected value, but with different sample sizes (denominator of proportions), have different means or expected values after this transformation. Overdispersion causes a larger deviation of the expected value after the transformation. Angular transformation should be avoided unless the sample size (denominator of proportions) is the same for all the proportions analyzed.