ifr_os_t_test performs t tests on the equality of means. It tests the
hypothesis that a sample has a mean equal to a hypothesized value.
Usage
ifr_os_t_test(
data,
x,
mu = 0,
alpha = 0.05,
alternative = c("both", "less", "greater", "all"),
...
)Arguments
- data
a
data.frameortibble- x
numeric; column in
data- mu
a number indicating the true value of the mean
- alpha
acceptable tolerance for type I error
- 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
ifr_os_t_test returns an object of class "ifr_os_t_test".
An object of class "ifr_os_t_test" is a list containing the
following components:
- mu
a number indicating the true value of the mean
- n
number of observations
- df
degrees of freedom
- Mean
observed mean of
x- stddev
standard deviation of
x- std_err
estimate of standard error
- test_stat
t statistic
- confint
confidence interval for the mean
- mean_diff
mean difference
- mean_diff_l
lower confidence limit for mean difference
- mean_diff_u
upper confidence limit for mean difference
- p_l
lower one-sided p-value
- p_u
upper one-sided p-value
- p
two sided p-value
- conf
confidence level
- type
alternative hypothesis
- var_name
name of
x
References
Sheskin, D. J. 2007. Handbook of Parametric and Nonparametric Statistical Procedures, 4th edition. : Chapman & Hall/CRC.
Examples
# lower tail
ifr_os_t_test(hsb, write, mu = 50, alternative = 'less')
#> One-Sample Statistics
#> ---------------------------------------------------------------------------------
#> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval]
#> ---------------------------------------------------------------------------------
#> write 200 52.775 0.6702 9.4786 -Inf 53.8828
#> ---------------------------------------------------------------------------------
#>
#> Lower Tail Test
#> ---------------
#>
#> Ho: mean(write) >=50
#> Ha: mean(write) <50
#> --------------------------------------------------------------------------------
#> Variable t DF Sig Mean Diff. [95% Conf. Interval]
#> --------------------------------------------------------------------------------
#> write 4.141 199 0.99997 2.775 -Inf 3.8828
#> --------------------------------------------------------------------------------
# upper tail
ifr_os_t_test(hsb, write, mu = 50, alternative = 'greater')
#> One-Sample Statistics
#> ---------------------------------------------------------------------------------
#> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval]
#> ---------------------------------------------------------------------------------
#> write 200 52.775 0.6702 9.4786 51.6678 Inf
#> ---------------------------------------------------------------------------------
#>
#> Upper Tail Test
#> ---------------
#>
#> Ho: mean(write) <=50
#> Ha: mean(write) >50
#> --------------------------------------------------------------------------------
#> Variable t DF Sig Mean Diff. [95% Conf. Interval]
#> --------------------------------------------------------------------------------
#> write 4.141 199 0.00003 2.775 1.6678 Inf
#> --------------------------------------------------------------------------------
# both tails
ifr_os_t_test(hsb, write, mu = 50, alternative = 'both')
#> One-Sample Statistics
#> ---------------------------------------------------------------------------------
#> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval]
#> ---------------------------------------------------------------------------------
#> write 200 52.775 0.6702 9.4786 51.4537 54.0969
#> ---------------------------------------------------------------------------------
#>
#> Two Tail Test
#> ---------------
#>
#> Ho: mean(write) ~=50
#> Ha: mean(write) !=50
#> --------------------------------------------------------------------------------
#> Variable t DF Sig Mean Diff. [95% Conf. Interval]
#> --------------------------------------------------------------------------------
#> write 4.141 199 0.00005 2.775 1.4537 4.0969
#> --------------------------------------------------------------------------------
# all tails
ifr_os_t_test(hsb, write, mu = 50, alternative = 'all')
#> One-Sample Statistics
#> ---------------------------------------------------------------------------------
#> Variable Obs Mean Std. Err. Std. Dev. [95% Conf. Interval]
#> ---------------------------------------------------------------------------------
#> write 200 52.775 0.6702 9.4786 51.4537 54.0969
#> ---------------------------------------------------------------------------------
#>
#> Ho: mean(write) ~=50
#>
#> Ha: mean < 50 Ha: mean ~= 50 Ha: mean > 50
#> t = 4.141 t = 4.141 t = 4.141
#> P < t = 0.99997 P > |t| = 0.00005 P > t = 0.00003