diff --git a/modules/lab4/lab4-4.ipynb b/modules/lab4/lab4-4.ipynb
index 22a1a3c6..3fa9d7a7 100644
--- a/modules/lab4/lab4-4.ipynb
+++ b/modules/lab4/lab4-4.ipynb
@@ -86,11 +86,11 @@
    "source": [
     "def mann_kendall(V, alpha=0.05):\n",
     "    '''Mann Kendall Test (adapted from original Matlab function)\n",
-    "       Performs original Mann-Kendall test of the null hypothesis of trend absence in the vector V,  \n",
-    "       against the alternative of trend.\n",
-    "       The result of the test is returned in H = False indicates a rejection of the null hypothesis at \n",
-    "       the alpha significance level. \n",
-    "       H = True indicates a failure to reject the null hypothesis at the alpha significance level.\n",
+    "       Performs original Mann-Kendall test of the null hypothesis of trend absence in the vector V, against the alternative of trend.\n",
+    "       \n",
+    "       The result of the test is returned in reject_null:\n",
+    "       reject_null = True indicates a rejection of the null hypothesis at the alpha significance level. \n",
+    "       reject_null = False indicates a failure to reject the null hypothesis at the alpha significance level.\n",
     "       \n",
     "       INPUTS:\n",
     "       V = time series [vector]\n",
@@ -148,9 +148,9 @@
     "    Zalpha = st.norm.ppf(1-alpha,0,1)\n",
     "    p_value = 2*(1-st.norm.cdf(abs(Z), 0, 1)) #Two-tailed test p-value\n",
     "\n",
-    "    H = abs(Z) > Zalpha\n",
+    "    reject_null = abs(Z) > Zalpha # reject null hypothesis only if abs(Z) > Zalpha\n",
     "    \n",
-    "    return H, p_value"
+    "    return reject_null, p_value"
    ]
   },
   {
@@ -181,11 +181,11 @@
    "source": [
     "alpha = 0.05\n",
     "\n",
-    "H, p_value = mann_kendall(snow_pillows['SLI_max'].values, alpha)\n",
-    "print('Can we reject the null hypothesis for Slide Canyon?\\n{}\\n'.format(H))\n",
+    "reject_null, p_value = mann_kendall(snow_pillows['SLI_max'].values, alpha)\n",
+    "print('Can we reject the null hypothesis for Slide Canyon?\\n{}\\n'.format(reject_null))\n",
     "\n",
-    "H, p_value = mann_kendall(snow_pillows['BLC_max'].values, alpha)\n",
-    "print('Can we reject the null hypothesis for Blue Canyon?\\n{}\\n'.format(H))"
+    "reject_null, p_value = mann_kendall(snow_pillows['BLC_max'].values, alpha)\n",
+    "print('Can we reject the null hypothesis for Blue Canyon?\\n{}\\n'.format(reject_null))"
    ]
   },
   {