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Compare correlations

Source: R/compare_cor.R
compare_cor.Rd

This function is a wrapper around psych::r.test.

Usage

compare_cor(data, r1, r2, data2 = NULL, by = NULL, ci = 0.95)

Arguments

data

A data frame

r1, r2

Names of variable for the first and second correlations

data2

Where to look for the r2 columns (if not provided, looked for on data).

by

Name of column to split data by. The column must have only 2 unique values. If provided, the correlation between r1 is compared between the two groups.

ci

Confidence level for correlations.

Value

A list of two data frames:

  1. The two correlations + their CIs

  2. The test results

Details

  • If data2 is provided, the correlation between r1 (in data) and r2 (in data2) is compared.

    • If r2 not provided, the correlation between r1 (in data) and r1 (in data2) is compared

  • If by is provided r1 (in data) is compared between the 2 groups.

  • Else, a test for the difference of two dependent correlations is conducted.

Examples

# Test dependent correlations ------------------
## different variables
compare_cor(mtcars, r1 = c("mpg", "hp"), r2 = c("drat", "am"))
#> $Correlations
#>       Variables          r   CI     CI_low    CI_high
#> r1  mpg with hp -0.7761684 0.95 -0.8852686 -0.5860994
#> r2 drat with am  0.7127111 0.95  0.4843991  0.8501319
#> 
#> $Test
#>                                                    Test         z           p
#> 1 Test of difference between two dependent correlations -6.133834 8.57858e-10
#> 

## 1 shared variable
compare_cor(mtcars, r1 = c("mpg", "hp"), r2 = c("mpg", "am"))
#> $Correlations
#>      Variables          r   CI     CI_low    CI_high
#> r1 mpg with hp -0.7761684 0.95 -0.8852686 -0.5860994
#> r2 mpg with am -0.2432043 0.95 -0.5456270  0.1152646
#> 
#> $Test
#>                                                      Test         t
#> 1 Test of difference between two correlated  correlations -5.563815
#>              p
#> 1 5.301858e-06
#> 



# Test independent correlations -----------------
## Different data sets
compare_cor(
  data = mtcars, r1 = c("mpg", "hp"),
  data2 = iris, r2 = c("Sepal.Length", "Sepal.Width")
)
#> $Correlations
#>                                Variables          r   CI     CI_low     CI_high
#> r1                   mpg with hp (data1) -0.7761684 0.95 -0.8852686 -0.58609941
#> r2 Sepal.Length with Sepal.Width (data2) -0.1175698 0.95 -0.2726932  0.04351158
#> 
#> $Test
#>                                                      Test        z            p
#> 1 Test of difference between two independent correlations 4.515732 6.309853e-06
#> 

## Groups
compare_cor(mtcars, r1 = c("mpg", "hp"), by = "am")
#> $Correlations
#>             Variables          r   CI     CI_low    CI_high
#> r1 mpg with hp (am=0) -0.8315065 0.95 -0.9332484 -0.6062733
#> r2 mpg with hp (am=1) -0.8006683 0.95 -0.9378951 -0.4467852
#> 
#> $Test
#>                                                      Test         z        p
#> 1 Test of difference between two independent correlations 0.2295313 0.818456
#>