## 6 AR Content Usability Evaluation and Results
### Result
This is because the system does not align with the users' preferences (67.92). Figure 22 presents the traditional Absolute Grading Scale (AGS) system for measuring usability evaluation scores, as proposed by [PERSON] et al. (2017). In this system, an \"A\" grade corresponds to a score of over 90 and up to 100, a \"B\" to a score over 80 and up to 90, a \"C\" to a score over 70 and up to 80, a \"D\" to a score over 60 and up to 70, and anything below that is graded as an \"F\". The use of this absolute grading system makes achieving an \"A\" grade, which requires a score above 90, virtually impossible. As an alternative, the scores obtained from the proposed usability evaluation were compared and analyzed using the curved rating scale (CGS) table proposed by [PERSON] and [PERSON] (2014, 2015). This CGS grading system stems from the preference for assigning grades based on a curve where a usability evaluation score of 68 is positioned at the center of the \"C\" range. [PERSON] et al. reviewed 241 studies and identified only 2 instances where the score exceeded 90. To provide a fairer evaluation allocation, they developed a curved grading scale for the average score using percentiles calculated as shown in Table 7. Additionally, a total of 446 survey and usability study data points were included to analyze \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{**Category**} & \multirow{3}{*}{**No**} & \multicolumn{2}{c}{**Document Manual**} & \multicolumn{2}{c}{**AR Content**} \\ \cline{3-6}  & & **Average** & \
\begin{tabular}{c} **Standard** \\ **Deviation** \\ \end{tabular} & **Average** &
\begin{tabular}{c} **Standard** \\ **Deviation** \\ \end{tabular} \\ \hline \multirow{6}{*}{System Usefulness} & 1 & 79.58 & 19.42 & 86.25 & 13.55 \\  & 2 & 77.08 & 16.32 & 82.50 & 14.10 \\  & 3 & 77.08 & 18.75 & 85.83 & 14.40 \\  & 4 & 73.75 & 19.20 & 85.83 & 13.89 \\  & 5 & 69.58 & 24.43 & 81.25 & 12.62 \\  & 6 & 73.33 & 19.90 & 87.08 & 13.86 \\  & 7 & 75.42 & 23.57 & 85.00 & 12.96 \\  & 8 & 75.83 & 22.31 & 85.83 & 12.83 \\ \hline \multirow{6}{*}{Information Quality} & 9 & 77.92 & 20.46 & 80.83 & 16.69 \\  & 10 & 75.83 & 20.31 & 73.33 & 15.92 \\  & 11 & 73.75 & 20.63 & 86.25 & 9.16 \\  & 12 & 71.25 & 21.01 & 83.33 & 9.99 \\  & 13 & 74.58 & 21.01 & 83.33 & 8.44 \\  & 14 & 70.83 & 20.93 & 76.25 & 14.07 \\  & 15 & 73.33 & 20.95 & 80.00 & 16.96 \\ \hline \multirow{3}{*}{Interface Quality} & 16 & 67.50 & 21.00 & 69.17 & 22.50 \\  & 17 & 68.75 & 18.94 & 67.92 & 21.81 \\  & 18 & 66.67 & 24.17 & 74.17 & 21.67 \\ \hline Overall Usability & 19 & 70.42 & 18.29 & 81.67 & 13.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Average and standard deviation for each CSUQ question between the document manual and AR content. Figure 22: The Bangor traditional AGS system. this grading system. According to [PERSON], although the CGS table is designed for SUS, it is also compatible with UMUX and CSUQ [46]. The AR content average scores for the UMUX and CSUQ surveys are 81.56 and 80.83, respectively. These scores correspond to a \"B\" grade on the AGS system, which is categorized as good and considered acceptable. The CGS system assigns an \"A\" grade, placing the scores within the 90-95 th percentile. This result confirms, as shown in Figure 22 of the usability evaluation of the air spring AR content, that the content is acceptable and falls within the 90-95 th percentile, indicating that it is highly useful. Based on the participants' feedback on the user experience evaluation, the researchers identified two main issues, as summarized in Table 8. Participants had difficulty understanding the interface's usage, often resorting to repeated touches to learn. Participants learned how to use the AR system but experienced significant inconvenience because commands were not executing properly along the way. Therefore, it is necessary to provide separate user manuals or instructions to ensure that the AR content is easily understandable for everyone.