如何在R中运行一种方差分析

Question

I've a dataset looking like this:

> print(mydata)
                col1                 col2                col3
1               0.819               0.851               0.874
2               0.972               0.703               0.821
3               0.891               0.790               0.951
4               0.839               0.799               0.819

I would like to know if there are significant differences between the three groups col1 , col2 and col3 . For this matter, my guess is that the best way is to run an anova test.

Please find below the script I used to produce the dataset, to run the test and the Error displayed by R:

> mydata <- data.frame(col1, col2, col3)
> accuracymetrics <- as.vector(mydata)
> anova(accuracymetrics)

Error in UseMethod("anova") : no applicable method for 'anova' applied to an object of class "data.frame"

It's the first time I'm running such an analysis in R so bear with me if this question is not interesting for the forum. Any input to solve this error is appreciated!

Answer 1

if I understood you correctly the three groups you are talking about are the three columns in your data. If this is the case you need to do two things:

First, reshape your data from wide to long format such that it looks like this

group | value
------------
grp1  | 0.819
grp1  | 0.972

This can easily be done with the tidyr package

library(tidyr)
longdata <- gather(mydata, group, value)

Second: you have to use aov instead of anova :

res.aov <- aov(value ~ group, data = longdata)
summary(res.aov)

Here you can find even more details. Hope this helps.