diff --git a/src/system-bookmarks/user-study.tex b/src/system-bookmarks/user-study.tex
index 8767127..a8ec736 100644
--- a/src/system-bookmarks/user-study.tex
+++ b/src/system-bookmarks/user-study.tex
@@ -69,10 +69,12 @@ The server is hosted on an Acer Aspire V3 with an Intel Core i7 3632QM processor
 The user is given a One Plus 5 that is connected to the server via Wi-fi.
 There is no artificial bandwidth limitation due to the fact that the bandwidth is already limited by the Wi-fi network and by the performances of the mobile device.
 
-\subsection{Results}
+\subsubsection{Participants}
 
 18 users participated in this user-study, 15 males and 3 females, average age is 20.7 and standard deviation is 0.53.
-We only proposed this user study to relatively young people to ensure they are used to mobile devices.
+We only proposed this user study to relatively young people to ensure they are used to mobile devices: this is a requirement for our user-study since navigating in a 3D scene on a mobile device is hard, and people who are not familiar with it will likely drop out of the experiment.
+
+\subsection{Results}
 
 \subsubsection{Qualitative results --- Interaction}