correlation.R

This function creates a publication-ready correlation table. If used correctly, the output displays a diagonally formatted correlation table with mean and standard deviation as the first rows and the cronbachs alpha values on the diagonal, if desired. See below how to use it.

Basic R function to call:

library(devtools)
source_url("https://lucasmaunz.org/download/correlation.R")

Alternatively: Download this script.

Correlation Table Example

This example shows how to generate a publication-ready APA-style correlation table in R using the correlation_matrix() and cor2flex() helper functions.

Load the functions

source("https://lucasmaunz.org/download/correlation.R")

Generate example data

We’ll simulate four variables with a known correlation structure so the output is easy to interpret.

set.seed(42)
n <- 100
 
x1 <- rnorm(n)
x2 <-  0.8 * x1 + rnorm(n, sd = 0.6)  # strong positive correlation with x1
x3 <- -0.5 * x1 + rnorm(n, sd = 0.9)  # moderate negative correlation with x1
x4 <- rnorm(n)                         # uncorrelated noise
 
df <- data.frame(x1, x2, x3, x4)

Build the correlation matrix

use = "lower" keeps only the lower triangle, digits = 2 rounds to two decimals, and leading_zero = FALSE strips the leading zero (APA style: .84 instead of 0.84). Significance is marked with * (p < .05), ** (p < .01), and *** (p < .001).

cor.mat <- correlation_matrix(df, digits = 2, use = "lower", leading_zero = FALSE)
cor.mat

   x1       x2       x3       x4
x1 " 1.00 " ""       ""       ""
x2 " .84***" " 1.00 " ""       ""
x3 "-.58***" "-.46***" " 1.00 " ""
x4 " .07  " " .07  " "-.07  " " 1.00 "

Add means and standard deviations (optional)

A common APA pattern is to show M and SD in the leftmost columns. sprintf("%.2f", ...) rounds and pads to two decimals in one step.

cor.mat <- data.frame(cor.mat)
cor.mat <- data.frame(
  M  = sprintf("%.2f", colMeans(df, na.rm = TRUE)),
  SD = sprintf("%.2f", sapply(df, sd, na.rm = TRUE)),
  cor.mat
)

Format as a publication-ready flextable

cor2flex() converts the data frame into a styled flextable with APA-style numeric column headers (1, 2, 3, …) and a Variable column on the left. Provide var_labels to use descriptive names instead of the raw column names.

labels <- c(
  "1. Nature Exposure",
  "2. Detachment",
  "3. Positive Activation",
  "4. Serenity"
)
 
ft <- cor2flex(cor.mat, var_labels = labels)
ft

Export to Word

Pass preview = "docx" to open the table directly in Word for copy-pasting into a manuscript.

print(ft, preview = "docx")

Quick alternative: copy to clipboard

For a fast paste into Excel or another spreadsheet, skip the flextable step and copy the data frame directly.

library(clipr)
write_clip(cor.mat)