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pgilad/chi_square_min_sample.r

Last active April 15, 2018 10:28
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Find minimum sample size to obtain minimum power test in non-centralized chi-square
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chi_square_min_sample.r
u <- c(0.1, 0.3, 0.5)
chi_df <- 3
target_power <- 0.9
chi_base <- qchisq(0.95, chi_df)
get_power <- function(n) {
return (pchisq(q = chi_base, df = chi_df, ncp = n * u %*% u, lower.tail = FALSE))
}
get_power(20)
get_power(30)
n_target <- optimize(function(n) { return(abs(get_power(n) - target_power))}, lower = 1, upper = 300)
print(ceiling(n_target$minimum))
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