## 3 Results
### Virtual Prototyping and Testing in the Lab (VRT)  
1. Quantitative comparative test  
During the quantitative comparative test, the students delivered some interesting insights. When looking at the questionnaire data, we see that the participants (\(n=27\)) rated the VR environment better in terms of interactivity, presence and realism (see Figure 7). However, more use-oriented items such as functionality (excerpt from the MARS questionnaire) and overall task difficulty do not seem to differ all that much. The normality tests (Appendix A, Table A1) indicate that the data regarding presence, task difficulty and functionality are not normally distributed, while the results for realism and interactivity are normally distributed. After running a paired samples t-test or a Wilcoxon signed rank on each element, it turned out that there were significant effects found for interactivity, presence and realism. According to our hypothesis, we expected the VR prototype to be rated as more realistic compared to the low-fidelity prototypes tested in the field. The results of the paired samples t-test confirm that the VR test (M = 5.6, SD = 1.64) was more realistic compared to the paper test (M = 3.75, SD = 2.29) (t(27) = 3.96, \(p=0.001\)). For the second hypothesis, we expected that the participants would feel more present when using the VR prototype compared to the low-fidelity prototype. The results of the Wilcoxon signed rank test confirm that the VR test (Mdn = 6) induced more presence than the paper test (Mdn = 3.5) (\(Z=-3.11\), \(p=0.002\)). According to our hypothesis, the participants should have experienced more interactivity when using the VR prototype compared to the low-fidelity prototypes. The results of the paired samples t-test confirm this effect where the VR test (M = 7.5, SD = 0.91) is more interactive than the paper test (M = 4.81, SD = 2.3) (t(27) = 6.13, \(p<0.001\)). Our hypothesis expected the participants to experience better functionality when using the VR prototype compared to the low-fidelity prototype. However, the \(p\)-value of the [PERSON] signed rank test was too high for statistical significance (Mdn(VR) = 6.5, Mdn(Paper) = 6.3) (\(Z=-1.292\), \(p=0.2\)). According to our hypothesis, we expected the participants to experience less difficulty when performing tasks with the VR prototype compared to the low-fidelity prototype. The \(p\)-value resulting from the linear mixed model analysis was too high for statistical significance (Mdn(VR) = 7.3, Mdn(Paper) = 6.85) (\(Z=-1.668\), \(p=0.098\)). When  
Figure 7: Results of comparative test between VR and paper prototyping resulting significant differences of interactivity, presence and realism. using \(\alpha=(0.05/8)\) as the Bonferroni correction to account for the family-wise error rate, the results do not differ. Qualitative reporting  
Control vs. validity: The VRT setup allowed for more control over the experienced scenario. The content expert mentioned that some people struggled with using the buttons; this could be easily resolved by giving a tutorial first;  
\"Some of my colleagues really couldn't handle VR properly. They sometimes said: I'm too old for this, I can't do this. Some things were just difficult such as picking up an object. Sometimes VR does not do what you would expect it to do.\" (Expert on content creation)  
Presence and realism: The perceived visual realism was quite high. The participants reported that they could imagine that they were in a pop-up lab rather than looking at several different screens. According to the experts interviewed, the main advantage that VR delivered in this research was a clear visual representation. The experts mentioned that VR brought the people working on the project closer together and that the VR prototype induced a lot of conversation. Lengthy discussions on the customers' journeys resulted from testing the VR prototype. This could mean that VR created the common ground to facilitate discussions as well.