tests/testthat/test-ttest.R

In inferr: Inferential Statistics

context("infer_os_t_test")

test_that("output from infer_os_t_test matches the expected output", {
  k <- infer_os_t_test(mtcars, mpg, mu = 50, alternative = "less")
  expect_equal(k$mu, 50)
  expect_equal(k$n, 32)
  expect_equal(k$df, 31)
  expect_equal(k$Mean, 20.0906)
  expect_equal(k$stddev, 6.0269)
  expect_equal(k$std_err, 1.0654)
  expect_equal(k$test_stat, -28.073)
  expect_equivalent(k$confint, c(-Inf, 21.8974))
  expect_equal(k$mean_diff_l, -Inf)
  expect_equal(k$mean_diff_u, -28.1026)
  expect_equal(k$mean_diff, -29.9094)
  expect_equal(k$p_l, 6.592161e-24)
  expect_equal(k$p_u, 1)
  expect_equal(k$p, 1.31843219487798e-23)
  expect_equal(k$conf, 0.95)
  expect_equivalent(k$type, "less")
  expect_equivalent(k$var_name, "mpg")

  k <- infer_os_t_test(mtcars, mpg, mu = 50, alternative = "greater")
  expect_equivalent(k$confint, c(18.2846, Inf))

  k <- infer_os_t_test(mtcars, mpg, mu = 50, alternative = "both")
  expect_equivalent(k$confint, c(17.9181, 22.2639))
})

test_that("infer_os_t_test throws the appropriate error", {
  expect_error(infer_os_t_test(hsb, race, mu = 50), "x must be numeric")
  expect_error(infer_os_t_test(mtcars, mpg, mu = "50"), "mu must be numeric")
  expect_error(infer_os_t_test(mtcars, mpg, mu = 50, alpha = "0.05"), "alpha must be numeric")
})

test_that("output from one sample t test is as expected when alternative is less", {
  x <- cat("                              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
--------------------------------------------------------------------------------")

  expect_output(print(infer_os_t_test(hsb, write, mu = 50, alternative = "less")), x)
})

test_that("output from one sample t test is as expected when alternative is greater", {
  x <- cat("                              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    0.99997       2.775         1.6678      Inf
--------------------------------------------------------------------------------")

  expect_output(print(infer_os_t_test(hsb, write, mu = 50, alternative = "greater")), x)
})

test_that("output from one sample t test is as expected when alternative is both", {
  x <- cat("                              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    0.99997       2.775         1.4537     4.0969
--------------------------------------------------------------------------------")

  expect_output(print(infer_os_t_test(hsb, write, mu = 50, alternative = "both")), x)
})

test_that("output from one sample t test is as expected when alternative is all", {
  x <- cat("                              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 = 1.0000             P > |t| = 0.0001             P > t = 0.0000")

  expect_output(print(infer_os_t_test(hsb, write, mu = 50, alternative = "all")), x)
})