tests/testthat/test_means.R

In statlab/permuter: permuter: Permutation Tests

set.seed(55)

context("One sample")
test_that("bad inputs", {
    expect_error(one_sample("k"), "numeric")
    expect_error(one_sample(data.frame(1:5)), "vector")
})

test_that("IPAT example from chapter 1", {
    data(ipat)
    d <- ipat$YA - ipat$YB
    distr <- one_sample(d)
    expect_equal(min(distr), -2.6)
    expect_equal(max(distr), 2.6)
    expect_equal(median(distr), 0)
})

context("Two sample")
test_that("bad inputs", {
    expect_error(two_sample("k", 4), "numeric")
    expect_error(two_sample(data.frame(1:5), 40), "vector")
})

test_that("jobs example from chapter 1", {
    data(job)
    group1 <- job[job$Y == 1, "X"]
    group2 <- job[job$Y == 2, "X"]
    observed <- mean(group1) - mean(group2)
    distr <- two_sample(group1, group2)
    expect_equal(min(distr), -16.875)
    expect_equal(max(distr), 18 + 1/3)
    expect_equal(median(distr), 0)
})

context("Stratified two sample")
test_that("within group means", {
    group <- c(rep(1, 4), rep(2, 4))
    stratum <- c("b", rep("a", 4), rep("b", 3))
    response <- 1:8
    groups <- unique(group)
    strata <- unique(stratum)
    
    diff_strat1 <- 1 - mean(6:8)
    diff_strat2 <- mean(2:4) - 5
    expected <- c(b = diff_strat1, a = diff_strat2)
    res <- within_group_mean(group, response, stratum, groups, strata)
    expect_equal(expected, res)
})


test_that("bad inputs", {
    expect_error(stratified_two_sample(4, "k", 5), "numeric")
    expect_error(stratified_two_sample(data.frame(1:5), 20, 40), "vector")
    expect_error(stratified_two_sample(5, 20, 40, stat = "lame"), "dictionary of stats")
})

test_that("simple example", {
    group <- c(rep(1, 4), rep(2, 4))
    stratum <- c("b", rep("a", 4), rep("b", 3))
    response <- 1:8
    
    set.seed(55)
    distr <- stratified_two_sample(group, response, stratum)
    expect_equal(min(distr), -4)
    expect_equal(median(distr), 0)
    expect_equal(max(distr), 4)
    
    set.seed(55)
    distr <- stratified_two_sample(group, response, stratum, stat = "mean_within_strata")
    expect_equal(min(distr), 1.333, tolerance = 0.001)
    expect_equal(median(distr), 4)
    expect_equal(max(distr), 9.333, tolerance = 0.001)
})

test_that("example from permute", {
    stratum <- rep(1:3, each = 10)
    group <- rep(rep(1:2, each = 5), 3)
    response <- rep(0, length(group))
    response[c(1, 2, 4, 10, 11, 12, 19, 20, 21)] <- 1
    
    set.seed(55)
    res <- stratified_two_sample(group, response, stratum, reps = 10000)
    expect_equal(mean(response[group == 1]) - mean(response[group == 2]), 0.2)
    expect_equal(c(Upper = 0.2169), t2p(0.2, res, "greater"))
})