First of all, I'm aware that I can use var.test(x, y) for inference on the ratio of two population variances, but my question is regarding inference on one population variance.
According to this source, I should use the function varTest() to conduct a one-sample test on population variance. However, I get an error code whenever I try this, as R could not find this function:
x <- rnorm(50, mean = 4, sd = 1)
varTest(x, sigma.squared = 1) # sigma.squared is our null hypothesis for population variance
Error in varTest(x, sigma.squared = 1) :
could not find function "varTest"
This is what happens if I try to use var.test() for a one sample test on population variance:
x <- rnorm(50, mean = 4, sd = 1)
var.test(x, sigma.squared = 1)
Error in var.test.default(x, sigma.squared = 1) :
argument "y" is missing, with no default
No surprise for the second error as I think var.test() is reserved only for inference on the ratio of two population variances.
Is it the case that I'm supposed to use the function varTest, but I simply don't have the package which contains that function installed?
Background Information: I'm running RStudio Version 1.3.959 on macOS Catalina Version 10.15.6 This is a video of the statistical test that I'm trying to conduct in R.
The function you link to is part of the EnvStats package. You need to install it and load it before you can execute the function:
install.packages("EnvStats")
library(EnvStats)
x <- rnorm(50, mean = 4, sd = 1)
varTest(x, sigma.squared = 1)
#>
#> Chi-Squared Test on Variance
#>
#> data: x
#> Chi-Squared = 28.224, df = 49, p-value = 0.01506
#> alternative hypothesis: true variance is not equal to 1
#> 95 percent confidence interval:
#> 0.4019175 0.8944284
#> sample estimates:
#> variance
#> 0.5759921