diff --git a/README.md b/README.md
index fa9f8891..bb24baca 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
-# DABEST-Python
-
+DABEST-Python
+================
 
 <!-- WARNING: THIS FILE WAS AUTOGENERATED! DO NOT EDIT! -->
 
diff --git a/dabest/_stats_tools/confint_2group_diff.py b/dabest/_stats_tools/confint_2group_diff.py
index 59b53894..5063b8d3 100644
--- a/dabest/_stats_tools/confint_2group_diff.py
+++ b/dabest/_stats_tools/confint_2group_diff.py
@@ -314,7 +314,10 @@ def compute_interval_limits(bias, acceleration, n_boots, ci=95):
 
 @njit(cache=True)
 def calculate_group_var(control_var, control_N, test_var, test_N):
-    return control_var / control_N + test_var / test_N
+    
+    pooled_var = ((control_N - 1) * control_var + (test_N - 1) * test_var) / (control_N + test_N - 2) 
+    
+    return pooled_var
 
 
 def calculate_weighted_delta(group_var, differences):
diff --git a/nbs/API/confint_2group_diff.ipynb b/nbs/API/confint_2group_diff.ipynb
index c5dc22da..29ca48ae 100644
--- a/nbs/API/confint_2group_diff.ipynb
+++ b/nbs/API/confint_2group_diff.ipynb
@@ -368,7 +368,10 @@
     "\n",
     "@njit(cache=True)\n",
     "def calculate_group_var(control_var, control_N, test_var, test_N):\n",
-    "    return control_var / control_N + test_var / test_N\n",
+    "    \n",
+    "    pooled_var = ((control_N - 1) * control_var + (test_N - 1) * test_var) / (control_N + test_N - 2) \n",
+    "    \n",
+    "    return pooled_var\n",
     "\n",
     "\n",
     "def calculate_weighted_delta(group_var, differences):\n",