diff --git a/R/utils.R b/R/utils.R
index bfc2e3d..ebc3ece 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -544,88 +544,33 @@ SimulationFunc <- function(data,
 
 }
 
-
-# ------------------------------------------------------------------------------
-#' Poisson Function for funnel plots for ratios and rates
-#'
-#' @noRd
-#'
-# ------------------------------------------------------------------------------
-
-
-poisson_cis <- function(z, x_a, x_b) {
-  # none of the following can occur based on Funnels.R
-  # if (any(z < 0, x_a < 0, x_b < 0, x_b < x_a, x_a %% 1 > 0, x_b %% 1 > 0))
-  #   return(NA)
-
-  q <- 1
-  tot <- 0
-  s <- 0
-  k <- 0
-
-  while (any(k <= z, q > tot * 1e-10)) {
-    tot <- tot + q
-    if (k >= x_a & k <= x_b) s <- s + q
-    if (tot > 1e30) {
-      s <- s / 1e30
-      tot <- tot / 1e30
-      q <- q / 1e30
-    }
-
-    k <- k + 1
-    q <- q * z / k
-
-  }
-  return(s / tot)
-}
-
-
 # ------------------------------------------------------------------------------
 #' Function for funnel plots for ratios and rates
 #'
 #' @noRd
-#'
+#' @import stats
 # ------------------------------------------------------------------------------
 
-poisson_funnel <- function(obs, p, side) {
-  # None of the following can occur based on Funnels.R
-  # if (any(obs < 0, p < 0, p > 1, obs %% 1 != 0)) return(NA)
-
-  v <- 0.5
-  dv <- 0.5
-
-  if (side == "low") {
-
-    # this is in the Excel macro code, but obs can't be 0 based on Funnels.R
-    # if (obs == 0) return(0)
-
-    while (dv > 1e-7) {
-      dv <- dv / 2
-
-      if (poisson_cis((1 + obs) * v / (1 - v),
-                      obs,
-                      10000000000) > p) {
-        v <- v - dv
-      } else {
-        v <- v + dv
-      }
-    }
-  } else if (side == "high") {
-
-    while (dv > 1e-7) {
-      dv <- dv / 2
-      if (poisson_cis((1 + obs) * v / (1 - v),
-                      0,
-                      obs) < p) {
-        v <- v - dv
-      } else {
-        v <- v + dv
-      }
+poisson_funnel <- function (obs, p, side) {
+  alp <- (p * 2) 
+  interval <- c(0, obs * 5 + 5)
+  
+  if(side == "high"){
+    fn <- function(obs, ans, alpha = alp) ppois(obs, ans) - alpha/2
+  } else if (side == "low"){
+    fn <- function(obs, ans, alpha = alp) 1 - ppois(obs, ans) + dpois(obs, ans) - alpha/2
+  } 
+  
+  if (obs == 0 & side == "low") {
+    result <- 0
+  } else {
+    if(exists("fn")){
+      result <- uniroot(fn, interval = interval, obs = obs)$root
+    } else {
+      result <- NA
     }
-
-  }
-  p <- (1 + obs) * v / (1 - v)
-  return(p)
+  } 
+  return(result)
 }
 
 # ------------------------------------------------------------------------------