effect.size: Cohen's-d effect size

In spatialEco: Spatial Analysis and Modelling Utilities

Cohen's-d effect size

Description

Cohen's-d effect size with pooled sd for a control and experimental group

Usage

effect.size(y, x, pooled = TRUE, conf.level = 0.95)

Arguments

y	A character or factor vector
x	A numeric vector, same length as y
pooled	Pooled or population standard deviation (TRUE/FALSE)
conf.level	Specified confidence interval. Default is 0.95

Value

An effect.size class object with x, y and a data.frame with columns for effect size, lower confidence interval, lower confidence interval. The row names of the data frame represent the levels in y

Note

This implementation will iterate through each class in y and treating a given class as the experimental group and all other classes as a control case. Each class had d and the confidence interval derived. A negative d indicate directionality with same magnitude. The expected range for d is 0 - 3 d is derived; ( mean(experimental group) - mean(control group) ) / sigma(p) pooled standard deviation is derived; sqrt( ( (Ne - 1) * sigma(e)^2 + (Nc - 1) * sigma(c)^2 ) / (Ne + Nc - 2) ) where; Ne, Nc = n of experimental and control groups.

Author(s)

Jeffrey S. Evans <[e-mail]>

References

Cohen, J., (1988) Statistical Power Analysis for the Behavioral Sciences (second ed.). Lawrence Erlbaum Associates.

Cohen, J (1992) A power primer. Psychological Bulletin 112(1):155-159

Examples

 ( es <- effect.size(iris$Species, iris$Sepal.Length) )
   plot(es)

spatialEco documentation built on Nov. 18, 2023, 1:13 a.m.