diff --git a/grain_size_tools/stereology_analysis_template.ipynb b/grain_size_tools/stereology_analysis_template.ipynb
index 2da4a86..13b483f 100644
--- a/grain_size_tools/stereology_analysis_template.ipynb
+++ b/grain_size_tools/stereology_analysis_template.ipynb
@@ -515,7 +515,7 @@
    "source": [
     "# lognormal parameters\n",
     "geomean = 36.05\n",
-    "std = np.log(1.63)\n",
+    "std = np.log(1.63)  # log(MSD)\n",
     "\n",
     "# set min and max grain size in the population\n",
     "min_size = 0\n",