> ####################################################################### > > # Nonparametric Bootstrap using bootstrap(), emp, bt, bca > > # function to compute the correlation and Fisher's z-transformation > > cor2 <- function(X){ + z1 <- X[,1] + z2 <- X[,2] + a <- cor(z1,z2) + b <- 0.50*(log((1+a)/(1-a)) - log((1+r.samp)/(1-r.samp)))/sqrt(n-3) + return(c(a,b)) + } > > r.boot <- bootstrap(X, cor2) Forming replications 1 to 100 Forming replications 101 to 200 Forming replications 201 to 300 Forming replications 301 to 400 Forming replications 401 to 500 Forming replications 501 to 600 Forming replications 601 to 700 Forming replications 701 to 800 Forming replications 801 to 900 Forming replications 901 to 1000 > > plot(r.boot) > > print(r.boot) Call: bootstrap(data = X, statistic = cor2) Number of Replications: 1000 Summary Statistics: Observed Bias Mean SE cor21 0.8766 -0.001532 0.875098 0.04647 cor22 0.0000 0.005074 0.005074 0.03748 > > secor <- r.boot$estimate[1,3] # location of the SE in the bootstrap data.frame > secor [1] 0.0465 > > r.boot.emp <- limits.emp(r.boot) > r.boot.emp 2.5% 5% 95% 97.5% cor21 0.7666 0.7901 0.9362 0.9413 cor22 -0.0672 -0.0557 0.0665 0.0747 > > finv025 <- r.boot.emp[2,1] > finv025 [1] -0.0672 > > finv975 <- r.boot.emp[2,4] > finv975 [1] 0.0747 > > r.btci <- c(r.samp - (secor*finv95), r.samp - (secor*finv05)) > r.btci [1] 0.824 0.962 > > r.boot.bca <- limits.bca(r.boot, details = T) > r.boot.bca $limits: 2.5% 5% 95% 97.5% cor21 0.7231 0.7518 0.9273 0.9344 cor22 -0.0876 -0.0755 0.0517 0.0614 $emp.probs: 2.5% 5% 95% 97.5% cor21 0.00573 0.0177 0.900 0.937 cor22 0.00417 0.0147 0.894 0.932 $z0: cor21 cor22 -0.103 -0.103 $acceleration: cor21 cor22 -0.0724 -0.0902 $group.size: [1] 1 > >