\subsection{Questionnaire}
\label{questions}

\figref{results_questions} presents the questionnaire results for each visual hand rendering.
Friedman tests indicated that all questions had statistically significant differences (\pinf{0.001}).
Pairwise Wilcoxon signed-rank tests with Holm-Bonferroni adjustment were then used each question results (\secref{metrics}):
\begin{itemize}
  \item \response{Difficulty}: \level{Occlusion} was considered more difficult than \level{Contour} (\p{0.02}), \level{Skeleton} (\p{0.01}), and \level{Mesh} (\p{0.03}).
  \item \response{Fatigue}: \level{None} was found more fatiguing than \level{Mesh} (\p{0.04}); And \level{Occlusion} more than \level{Skeleton} (\p{0.02}) and \level{Mesh} (\p{0.02}).
  \item \response{Precision}: \level{None} was considered less precise than \level{Skeleton} (\p{0.02}) and \level{Mesh} (\p{0.02}); And \level{Occlusion} more than \level{Contour} (\p{0.02}), \level{Skeleton} (\p{0.006}), and \level{Mesh} (\p{0.02}).
  \item \response{Performance}: \level{Occlusion} was lower than \level{Contour} (\p{0.02}), \level{Skeleton} (\p{0.006}), and \level{Mesh} (\p{0.03}).
  \item \response{Efficiency}: \level{Occlusion} was found less efficient than \level{Contour} (\p{0.01}), \level{Skeleton} (\p{0.02}), and \level{Mesh} (\p{0.02}).
  \item \response{Rating}: \level{Occlusion} was rated lower than \level{Contour} (\p{0.02}) and \level{Skeleton} (\p{0.03}).
\end{itemize}

In summary, \level{Occlusion} was worse than \level{Skeleton} for all questions, and worse than \level{Contour} and \level{Mesh} on 5 over 6 questions.
Results of \response{Difficulty}, \response{Performance}, and \response{Precision} questions are consistent in that way.
Moreover, having no visible visual \factor{Hand} rendering was felt by users fatiguing and less precise than having one.
Surprisingly, no clear consensus was found on \response{Rating}.
Each visual hand rendering, except for \level{Occlusion}, had simultaneously received the minimum and maximum possible notes.

\begin{subfigs}{results_questions}{Boxplots of the questionnaire results for each visual hand rendering.}[
    Pairwise Wilcoxon signed-rank tests with Holm-Bonferroni adjustment: ** is \pinf{0.01} and * is \pinf{0.05}.
    Lower is better for \textbf{(a)} difficulty and \textbf{(b)} fatigue.
    Higher is better for \textbf{(d)} performance, \textbf{(d)} precision, \textbf{(e)} efficiency, and \textbf{(f)} rating.
  ]
  \subfig[0.4]{results/Question-Difficulty}
  \subfig[0.4]{results/Question-Fatigue}
  \par
  \subfig[0.4]{results/Question-Precision}
  \subfig[0.4]{results/Question-Performance}
  \par
  \subfig[0.4]{results/Question-Efficiency}
  \subfig[0.4]{results/Question-Rating}
\end{subfigs}
