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How to perform Friedman test in R?
To perform Friedman test in R, we can follow the below steps −
- First of all, create a matrix.
- Then, use friedman.test function to perform the Friedman test.
Example1
Create the matrix
Let's create a data matrix as shown below −
First<-sample(1:100,20) Second<-sample(1:100,20) Third<-sample(1:100,20) Fourth<-sample(1:100,20) Period<-matrix(c(First,Second,Third,Fourth),byrow=FALSE,nrow=20) Period
On executing, the above script generates the below output(this output will vary on your system due to randomization) −
[,1] [,2] [,3] [,4] [1,] 56 19 61 100 [2,] 16 1 89 82 [3,] 34 18 13 13 [4,] 85 85 35 55 [5,] 10 29 42 79 [6,] 99 52 11 92 [7,] 27 42 87 86 [8,] 42 26 6 63 [9,] 19 3 90 16 [10,] 48 80 93 4 [11,] 89 43 94 52 [12,] 46 62 54 30 [13,] 61 68 57 71 [14,] 5 2 64 64 [15,] 15 93 45 91 [16,] 86 61 28 36 [17,] 66 53 84 28 [18,] 80 90 73 33 [19,] 18 23 7 24 [20,] 26 73 95 2
Perform Friedman test
Using friedman.test function to perform the test on data in Period −
First<-sample(1:100,20) Second<-sample(1:100,20) Third<-sample(1:100,20) Fourth<-sample(1:100,20) Period<-matrix(c(First,Second,Third,Fourth),byrow=FALSE,nrow=20) friedman.test(Period)
Output
Friedman rank sum test data: Period Friedman chi-squared = 0.19797, df = 3, p-value = 0.9779
Example2
Create the matrix
Let's create a data matrix as shown below −
Jan<-round(rnorm(20),2) Feb<-round(rnorm(20),2) Mar<-round(rnorm(20),2) Apr<-round(rnorm(20),2) May<-round(rnorm(20),2) Time<-matrix(c(Jan,Feb,Mar,Apr,May),byrow=FALSE,nrow=20) Time
On executing, the above script generates the below output(this output will vary on your system due to randomization) −
Output
[,1] [,2] [,3] [,4] [,5] [1,] 1.30 -1.21 -0.26 0.94 1.19 [2,] 1.14 -0.77 -1.54 0.67 1.77 [3,] 0.18 -0.50 0.72 0.76 -1.58 [4,] 1.51 0.13 2.71 0.51 0.62 [5,] -1.10 0.09 0.47 0.25 0.26 [6,] 1.31 0.51 -1.79 -1.67 0.32 [7,] 0.00 0.59 0.20 0.55 -0.20 [8,] 1.25 -0.91 -1.34 1.33 0.07 [9,] -0.19 -1.39 0.09 -2.08 -1.63 [10,] 0.66 1.17 -0.66 -0.02 -0.07 [11,] 0.05 -1.31 0.55 0.68 0.97 [12,] 1.57 -2.80 1.00 -1.55 -1.90 [13,] -0.67 0.29 0.60 2.28 1.34 [14,] 0.43 -3.66 -0.23 0.41 0.69 [15,] -0.56 0.11 0.60 1.09 -1.34 [16,] 1.87 0.48 0.49 -1.00 0.91 [17,] 1.01 0.64 0.74 -0.88 1.20 [18,] 0.90 -0.43 -0.61 0.27 0.10 [19,] 1.98 -0.54 1.02 0.89 -0.52 [20,] 0.11 -1.29 2.31 -0.18 1.41
Perform Friedman test
Using friedman.test function to perform the test on data in Period −
Jan<-round(rnorm(20),2) Feb<-round(rnorm(20),2) Mar<-round(rnorm(20),2) Apr<-round(rnorm(20),2) May<-round(rnorm(20),2) Time<-matrix(c(Jan,Feb,Mar,Apr,May),byrow=FALSE,nrow=20) friedman.test(Time)
Output
Friedman rank sum test data: Time Friedman chi-squared = 8.92, df = 4, p-value = 0.06313
Updated on: 14-Aug-2021
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