[Power analysis and sample size estimation with R] #R

power-analysis.R

# See <https://rpubs.com/mbounthavong/sample_size_power_analysis_R>

library(pwr)

# Sample size estimations for two proportions
# `pwr::ES.h()` computes effect size for two proportions
# n provides required sample size

p0 <- pwr.2p.test(h = ES.h(p1 = 0.60, p2 = 0.50), sig.level = 0.05, power = .80)
plot(p0)

# Power analysis for two proportions

p1 <- seq(0.5, 1.0, 0.05) # proportion of responders
power1 <-pwr.2p.test(h = ES.h(p1 = p1, p2 = 0.50),
                     n = 388,
                     sig.level = 0.05)
powerchange <- data.frame(p1, power = power1$power * 100)
plot(powerchange$p1, 
     powerchange$power, 
     type = "b", 
     xlab = "Proportion of Responders in Treatment A", 
     ylab = "Power (%)")