infer_os_var_test performs tests on the equality of standard deviations (variances).It tests that the standard deviation of a sample is equal to a hypothesized value.

infer_os_var_test(data, x, sd, confint = 0.95, alternative = c("both",
  "less", "greater", "all"), ...)

Arguments

data

a data.frame or tibble

x

numeric; column in data

sd

hypothesised standard deviation

confint

confidence level

alternative

a character string specifying the alternative hypothesis, must be one of "both" (default), "greater", "less" or "all". You can specify just the initial letter

...

additional arguments passed to or from other methods

Value

infer_os_var_test returns an object of class "infer_os_var_test". An object of class "infer_os_var_test" is a list containing the following components:

n

number of observations

sd

hypothesised standard deviation of x

sigma

observed standard deviation

se

estimated standard error

chi

chi-square statistic

df

degrees of freedom

p_lower

lower one-sided p-value

p_upper

upper one-sided p-value

p_two

two-sided p-value

xbar

mean of x

c_lwr

lower confidence limit of standard deviation

c_upr

upper confidence limit of standard deviation

var_name

name of x

conf

confidence level

type

alternative hypothesis

Deprecated Function

os_vartest() has been deprecated. Instead use infer_os_var_test().

References

Sheskin, D. J. 2007. Handbook of Parametric and Nonparametric Statistical Procedures, 4th edition. : Chapman & Hall/CRC.

See also

Examples

# lower tail infer_os_var_test(mtcars, mpg, 5, alternative = 'less')
#> One-Sample Statistics #> ----------------------------------------------------------------------------- #> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] #> ----------------------------------------------------------------------------- #> mpg 32 20.0906 1.0654 6.0269 3.8737 10.6527 #> ----------------------------------------------------------------------------- #> #> Lower Tail Test #> --------------- #> Ho: sd(mpg) >= 5 #> Ha: sd(mpg) < 5 #> #> Chi-Square Test for Variance #> ------------------------------------- #> Variable c DF Sig #> ------------------------------------- #> mpg 45.042 31 0.9506 #> -------------------------------------
# upper tail infer_os_var_test(mtcars, mpg, 5, alternative = 'greater')
#> One-Sample Statistics #> ----------------------------------------------------------------------------- #> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] #> ----------------------------------------------------------------------------- #> mpg 32 20.0906 1.0654 6.0269 3.8737 10.6527 #> ----------------------------------------------------------------------------- #> #> Upper Tail Test #> --------------- #> Ho: sd(mpg) <= 5 #> Ha: sd(mpg) > 5 #> #> Chi-Square Test for Variance #> ------------------------------------- #> Variable c DF Sig #> ------------------------------------- #> mpg 45.042 31 0.0494 #> -------------------------------------
# both tails infer_os_var_test(mtcars, mpg, 5, alternative = 'both')
#> One-Sample Statistics #> ----------------------------------------------------------------------------- #> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] #> ----------------------------------------------------------------------------- #> mpg 32 20.0906 1.0654 6.0269 3.8737 10.6527 #> ----------------------------------------------------------------------------- #> #> Two Tail Test #> --------------- #> Ho: sd(mpg) = 5 #> Ha: sd(mpg) != 5 #> #> Chi-Square Test for Variance #> ------------------------------------- #> Variable c DF Sig #> ------------------------------------- #> mpg 45.042 31 0.0988 #> -------------------------------------
# all tails infer_os_var_test(mtcars, mpg, 5, alternative = 'all')
#> One-Sample Statistics #> ----------------------------------------------------------------------------- #> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval] #> ----------------------------------------------------------------------------- #> mpg 32 20.0906 1.0654 6.0269 3.8737 10.6527 #> ----------------------------------------------------------------------------- #> #> Ho: sd(mpg) = 5 #> #> Ha: sd < 5 Ha: sd != 5 Ha: sd > 5 #> c = 45.0419 c = 45.0419 c = 45.0419 #> Pr(C < c) = 0.9506 2 * Pr(C > c) = 0.0988 Pr(C > c) = 0.0494