Power_Analysis.md

Power Analysis

Jesse Cambon 22 November, 2019

Check with https://www.stat.ubc.ca/~rollin/stats/ssize/b2.html

library(pwr)
pwr.2p.test(
       h=ES.h(0.6,0.8),
       n=NULL,
       sig.level=0.05,
       power=0.80,
       alternative="two.sided")

## 
##      Difference of proportion power calculation for binomial distribution (arcsine transformation) 
## 
##               h = 0.4421432
##               n = 80.29912
##       sig.level = 0.05
##           power = 0.8
##     alternative = two.sided
## 
## NOTE: same sample sizes

library(pwr)
power.prop.test(n = NULL, 
                p1 = .6, 
                p2 = .8,
                power=0.8,
                sig.level=0.05,
                alternative="two.sided"
                ) 

## 
##      Two-sample comparison of proportions power calculation 
## 
##               n = 81.22424
##              p1 = 0.6
##              p2 = 0.8
##       sig.level = 0.05
##           power = 0.8
##     alternative = two.sided
## 
## NOTE: n is number in *each* group

Additional References

• Biostat Handbook – Power Analysis
• Biostat Handbook - Hypothesis Testing
• UCLA Intro to Power Analysis
• An online power calculator for proportions
• The pwr R package – a popular R package used for power analysis