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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.

Phil
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Arif AH
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1 Answers1

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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
Vincent
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