Merge pull request #270 from Merck/269-correct-milestone-z-statistcis

Correct the denominator of the z-score of milestone tests
Merck · Aug 16, 2024 · 58d45ce · 58d45ce
2 parents b2b431c + f251d24
commit 58d45ce
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diff --git a/DESCRIPTION b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: simtrial
 Type: Package
 Title: Clinical Trial Simulation
-Version: 0.4.1.7
+Version: 0.4.1.8
 Authors@R: c(
     person("Keaven", "Anderson", email = "keaven_anderson@merck.com", role = c("aut")),
     person("Yujie", "Zhao", email = "yujie.zhao@merck.com", role =  c("ctb","cre")),

diff --git a/R/milestone.R b/R/milestone.R
@@ -84,10 +84,10 @@ milestone <- function(data, ms_time, test_type = c("log-log", "naive")) {
   } else {
     if (test_type == "naive") {
       z_numerator <- surv_diff
-      z_denominator <- surv_exp * sqrt(sigma2_exp) + surv_ctrl * sqrt(sigma2_ctrl)
+      z_denominator <- sqrt(surv_exp^2 * sigma2_exp + surv_ctrl^2 * sigma2_ctrl)
     } else if (test_type == "log-log") {
-      z_numerator <- log(-log(surv_exp)) - log(-log(surv_ctrl))
-      z_denominator <- sqrt(sigma2_exp) / log(surv_exp) + sqrt(sigma2_ctrl) / log(surv_ctrl)
+      z_numerator <- -(log(-log(surv_exp)) - log(-log(surv_ctrl)))
+      z_denominator <- sqrt(sigma2_exp / log(surv_exp)^2 + sigma2_ctrl / log(surv_ctrl)^2)
     }
   }
 

diff --git a/tests/testthat/helper-sim_gs_n.R b/tests/testthat/helper-sim_gs_n.R