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context("Known results for the dataset provided in DIN 32645")
require(chemCal)
m <- lm(y ~ x, data = din32645)
prediction <- inverse.predict(m, 3500, alpha = 0.01)
test_that("We get correct confidence intervals", {
# Result collected from Procontrol 3.1 (isomehr GmbH)
expect_equal(round(prediction$Confidence, 5), 0.07434)
})
test_that("We get a correct critical value", {
crit <- lod(m, alpha = 0.01, beta = 0.5)
# DIN 32645 gives 0.07 for the critical value
# (decision limit, "Nachweisgrenze")
expect_equal(round(crit$x, 2), 0.07)
# According to Dintest test data, we should get 0.0698
expect_equal(round(crit$x, 4), 0.0698)
})
test_that("We get a correct smalles detectable value using the DIN method", {
lod.din <- lod(m, alpha = 0.01, beta = 0.01, method = "din")
# DIN 32645 gives 0.14 for the smallest detectable value ("Erfassungsgrenze")
expect_equal(round(lod.din$x, 2), 0.14)
})
test_that("We get a correct limit of quantification", {
loq.din <- loq(m, alpha = 0.01)
# The value cited for Procontrol 3.1 (0.2121) deviates
# at the last digit, so we only test for three digits
expect_equal(round(loq.din$x, 3), 0.212)
})
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