Merge pull request #58 from WorldHealthOrganization/fix-overflow

Fix overflow in zscore estimates
WorldHealthOrganization · Nov 1, 2024 · e715811 · e715811
2 parents 9d92329 + eb2db42
commit e715811
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diff --git a/R/prevalence-simple.R b/R/prevalence-simple.R
@@ -162,7 +162,7 @@ sample_size <- function(x, N, empty_data_prototype) {
 }
 
 sample_se <- function(x, x_mean, n, N) {
-  scale <- N / (N - 1) * 1 / (n * n)
+  scale <- N / (N - 1)
   x_deviation <- x - x_mean
-  sqrt(sum(scale * x_deviation * x_deviation))
+  sqrt(scale)/n * sqrt(sum(x_deviation * x_deviation))
 }
diff --git a/tests/testthat/test-prevalence-simple-estimates.R b/tests/testthat/test-prevalence-simple-estimates.R
@@ -30,3 +30,10 @@ test_that("survey and approximation yield are equal within tolerance", {
     expect_equal(res_simple[[!!col]], res_survey[[!!col]], tolerance = 0.0001)
   }
 })
+
+test_that("zscore estimates should not overflow", {
+  x <- rnorm(100000)
+  expect_no_warning(
+    zscore_estimate(x, length(x), data.frame())
+  )
+})