# tests/testthat/test-levene.R In rsquaredacademy/inferr: Inferential Statistics

```context("levene-test")

test_that("output from infer_levene_test matches the expected result", {
mt <- mtcars
mt\$cyl <- as.factor(mt\$cyl)

k <- infer_levene_test(mt, mpg, group_var = cyl)
expect_equal(k\$bf, 6.4843)
expect_equal(k\$p_bf, 0.0047)
expect_equal(k\$lev, 5.5071)
expect_equal(k\$p_lev, 0.0094)
expect_equal(k\$bft, 6.2047)
expect_equal(k\$p_bft, 0.0057)
expect_equivalent(as.vector(k\$avgs), c(26.66, 19.74, 15.10))
expect_equivalent(as.vector(k\$sds), c(4.51, 1.45, 2.56))
expect_equal(k\$avg, 20.09)
expect_equal(k\$sd, 6.03)
expect_equal(k\$n, 32)
expect_equivalent(k\$levs, c("4", "6", "8"))
expect_equal(k\$n_df, 2)
expect_equal(k\$d_df, 29)
expect_equivalent(as.vector(k\$lens), c(11, 7, 14))
})

test_that("output from infer_levene_test matches the expected result", {
k <- infer_levene_test(mtcars, mpg, qsec)
expect_equal(k\$bf, 24.3932)
expect_equal(k\$p_bf, 0)
expect_equal(k\$lev, 20.9464)
expect_equal(k\$p_lev, 0)
expect_equal(k\$bft, 22.7064)
expect_equal(k\$p_bft, 0)
expect_equivalent(as.vector(k\$avgs), c(20.09, 17.85))
expect_equivalent(as.vector(k\$sds), c(6.03, 1.79))
expect_equal(k\$avg, 18.97)
expect_equal(k\$sd, 4.55)
expect_equal(k\$n, 64)
expect_equivalent(k\$levs, c("0", "1"))
expect_equal(k\$n_df, 1)
expect_equal(k\$d_df, 62)
expect_equivalent(as.vector(k\$lens), c(32, 32))
})

test_that("output from levene test is as expected", {
x <- cat("           Summary Statistics
Levels    Frequency    Mean     Std. Dev
-----------------------------------------
1          24        46.67      10.24
2          11        51.91      7.66
3          20        46.8       7.12
4          145       53.92      10.28
-----------------------------------------
Total        200       52.23      10.25
-----------------------------------------

Test Statistics
-------------------------------------------------------------------------
Statistic                            Num DF    Den DF         F    Pr > F
-------------------------------------------------------------------------
Brown and Forsythe                        3       196      3.44    0.0179
Levene                                    3       196    3.4792     0.017
Brown and Forsythe (Trimmed Mean)         3       196    3.3936     0.019
-------------------------------------------------------------------------")

expect_equivalent(print(infer_levene_test(hsb, read, group_var = race)), x)
})
```
rsquaredacademy/inferr documentation built on Aug. 28, 2019, 8:08 a.m.