Created
August 25, 2015 12:21
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correlationL <- list() | |
i <- 1 | |
for (r in seq(.75, .95, .05)){ # Correlations | |
for (n in seq(10, 1000, 10)){ # Sample sizes | |
z <- atanh(r) # Fisher's transformation | |
sez <- 1 / sqrt(n - 3) # SE of transformed variable | |
lower <- z - (1.96 * sez) | |
upper <- z + (1.96 * sez) | |
lowert <- (exp(2 * lower) - 1) / (exp(2 * lower) + 1) # Back-transform | |
uppert <- (exp(2 * upper) - 1) / (exp(2 * upper) + 1) # Back-transform | |
correlationL[i] <- as.data.frame(c(r, n, z, sez, lower, upper, | |
lowert, uppert)) | |
i <- i + 1 | |
} | |
} | |
correlationDf <- as.data.frame(do.call(rbind, correlationL)) | |
colnames(correlationDf) <- c("Correlation", "n", "z", "sez", "lowerz", | |
"upperz", "lowerR", "upperR") | |
# Plot the 95% CI for correlations at different sample sizes, all in one plot | |
ggplot(correlationDf, | |
aes(x = n, y = Correlation, ymin = lowerR, ymax = upperR, | |
group = factor(Correlation))) + | |
geom_ribbon(aes(fill = factor(Correlation)), color = "black", alpha = .5) + | |
geom_line(aes(alpha = n), color = "white", show_guide = F) + | |
geom_vline(x = 550, color = "red") + | |
coord_cartesian(ylim = c(.6, 1)) + | |
ylab("Correlation") + | |
xlab("Sample size") + | |
theme_bw() + | |
theme(text = element_text (color = "black", family = "serif"), | |
panel.border = element_blank(), | |
panel.grid.major = element_line(colour = "grey70", size = 0.2)) + | |
scale_fill_brewer(name = "Correlation", palette = "Set1") |
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