## 6 Results
### Usability, Usefulness and Ease of Use of Virtual Reality-Based System in Reducing Stress  
(i) The usability of the virtual reality-based therapy system.  
The usability of the system was measured by SUS items. Analysis performed resulted in the SUS average score of 78.1. According to [PERSON] et al. [45], a SUS score of 78.1 was interpreted as \"good\" with acceptable acceptability ranges. Meanwhile, when the score was interpreted according to a curved grading scale by [PERSON] and [PERSON] [46], the usability score fell into the A-category.  
(ii) The usefulness and ease of use of the virtual reality-based therapy system.  
The usefulness and ease of use of the system were determined based on the score of TAM. As for the usefulness, the mean score recorded was 5.71. One sample \(t\)-test conducted resulted in a significant difference from the usefulness mean value as compared to the mean of the scale. The result of the t-test indicated that the mean value of the perceived usefulness of the system (M = 5.71, SD = 0.78) was significantly higher than the mean of the scale used of 4; t(39) = 13.920, \(p=0.000<0.05\).  
In addition to the usefulness result obtained from the TAM instrument, this study also evaluated the usefulness of the system based on a perceived usefulness rating. The scores of the usefulness were grouped into four categories, which were (i) useless, (ii) somewhat useful, (iii) useful and (iv) very useful. The rescaling of the 10-point scale to 4-point scale feedback was performed based on an approach proposed by [PERSON] [44].  
The results of the analysis revealed that the majority of the participants rated the system as useful in reducing stress. Thirty-five participants (87.50%) agreed that the system was useful (with feedback of useful and very useful). Five participants (12.50%) rated the system as somewhat useful in reducing stress. None of the participants rated the system as useless in reducing stress. Figure 6 shows the graph of the perceived usefulness of the system in reducing stress.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Physiological Measures** & **Before** & **After** & **t** & **df** & **p** \\ \hline Systolic blood pressure (mmHg) & 120.23 \(\pm\) 19.00 & 116.43 \(\pm\) 17.44 & 1.64 & 39 & 0.109 \\ Diastolic blood pressure (mmHg) & 78.38 \(\pm\) 15.24 & 78.00 \(\pm\) 11.75 & 0.22 & 39 & 0.828 \\ Pulse rate (bpm) & 82.40 \(\pm\) 14.01 & 81.10 \(\pm\) 13.58 & 1.30 & 39 & 0.200 \\ \hline \end{tabular}
\end{table}
Table 7: Comparison of the physiological measures before and after the therapy sessions.  
Figure 5: Perceived effectiveness of the system in reducing stress.  
The one-sample t-test performed returned an encouraging result where the mean value of perceived usefulness of the system in reducing stress (M = 7.630, SD =1.409) was significantly higher than the mean of the scale of 5.5; t(39) = 9.542, \(p\) = 0.000 \(<\) 0.05.  
Meanwhile, the ease-of-use items recorded a mean value of 6.07. The result of the one-sample \(t\)-test conducted showed a significant difference between the ease-of-use mean value, as compared to the mean of the scale, which was 4. The mean value of perceived ease of use of the system that implemented the proposed framework (M = 6.071, SD = 0.751) was significantly higher than the mean of the scale of 4; t(39) = 17.440, \(p\) = 0.000 \(<\) 0.05.