diff --git a/notebooks/chapter_1_introduction/tutorial_4_why_modeling_is_hard.ipynb b/notebooks/chapter_1_introduction/tutorial_4_why_modeling_is_hard.ipynb
index e9c4d70..195770b 100644
--- a/notebooks/chapter_1_introduction/tutorial_4_why_modeling_is_hard.ipynb
+++ b/notebooks/chapter_1_introduction/tutorial_4_why_modeling_is_hard.ipynb
@@ -489,7 +489,9 @@
     "This means the non-linear parameter space has a dimensionality of N=15, making it significantly more complex \n",
     "than the simpler model we fitted in the previous tutorial.\n",
     "\n",
-    "Consequently, the non-linear search takes slightly longer to run but still completes in under a minute."
+    "Consequently, this 15-parameter search can take several minutes. A measured run on a four-core machine took\n",
+    "about six and a half minutes; your runtime will depend on the hardware, available cores and sampling trajectory.\n",
+    "The progress display below lets you follow the search while it runs."
    ]
   },
   {
@@ -501,7 +503,8 @@
     "print(\n",
     "    \"\"\"\n",
     "    The non-linear search has begun running.\n",
-    "    This Jupyter notebook cell with progress once the search has completed - this could take a few minutes!\n",
+    "    This Jupyter notebook cell will progress once the search has completed - allow several minutes\n",
+    "    (about six and a half minutes in one measured run; your runtime may differ).\n",
     "    \"\"\"\n",
     ")\n",
     "\n",
diff --git a/scripts/chapter_1_introduction/tutorial_4_why_modeling_is_hard.py b/scripts/chapter_1_introduction/tutorial_4_why_modeling_is_hard.py
index 9aaf41b..17b2b1e 100644
--- a/scripts/chapter_1_introduction/tutorial_4_why_modeling_is_hard.py
+++ b/scripts/chapter_1_introduction/tutorial_4_why_modeling_is_hard.py
@@ -338,14 +338,17 @@ def model_data_from_instance(self, instance):
 This means the non-linear parameter space has a dimensionality of N=15, making it significantly more complex 
 than the simpler model we fitted in the previous tutorial.
 
-Consequently, the non-linear search takes slightly longer to run but still completes in under a minute.
+Consequently, this 15-parameter search can take several minutes. A measured run on a four-core machine took
+about six and a half minutes; your runtime will depend on the hardware, available cores and sampling trajectory.
+The progress display below lets you follow the search while it runs.
 """
 analysis = Analysis(data=data, noise_map=noise_map)
 
 print(
     """
     The non-linear search has begun running.
-    This Jupyter notebook cell with progress once the search has completed - this could take a few minutes!
+    This Jupyter notebook cell will progress once the search has completed - allow several minutes
+    (about six and a half minutes in one measured run; your runtime may differ).
     """
 )