## 4 Results
### The Effect of Factor Pairs  
After the factors (variables) were analyzed one by one, the investigation continued with pairs. All possible combinations were made and were compared to each other. These combinations and their Intercept variables are the following as shown in Table 1:  
As can be seen in Table 1, the pair of 45\({}^{\circ}\) FoV & \(-\)15\({}^{\circ}\) camera rotation has the largest estimate of seconds, while the pair of desktop display & 1.5:1 contrast ratio and the desktop display have the smallest. If the pairs are looked at, it can also be suspected that when the \(-\)15\({}^{\circ}\) camera rotations are paired with another factor, the estimates become quite large. These estimates are the largest ones. Similarly, when the 1.5:1 contrast ratio is paired with another factor, the estimates decrease. These estimates are the smallest ones. The significant pairs resulting from the comparison can be seen in Figure 3 in the form of 95% CIs. From this point onward, the following new abbreviations are used: ROT for camera rotation, CR for contrast ratio, DD for desktop display, GVR for the Gear VR, SH ON for turned on shadows, and lastly, SH OFF for turned off shadows. As illustrated in Figure 3, there are 75 pairs with significant decreases and increases in completion times. 23 pairs decrease test completion times significantly, while 52 increase them. The largest significant decrease is in the case of 75\({}^{\circ}\) FoV and \(-\)45\({}^{\circ}\) camera rotation, while the largest significant increase is in the case of the Gear VR and 7:1 contrast ratio. \begin{table}
\begin{tabular}{c c c c} \hline
**Pairs** & **Intercept Levels of the Pairs** & **Estimate** & **Standard Error** \\ \hline FoV \& Camera rotation & 45\({}^{\circ}\) \& \(-\)15\({}^{\circ}\) & 235.153 s \\ FoV \& Contrast ratio & 45\({}^{\circ}\) \& 1.5:1 & 142.204 s \\ FoV \& Display device & 45\({}^{\circ}\) \& desktop display & 189.449 s \\ FoV \& Shadows & 45\({}^{\circ}\) \& shadows on & 195.200 s \\ Camera rotation \& Shadows & \(-\)15\({}^{\circ}\) \& shadows on & 233.400 s \\ Camera rotation \& Display device & \(-\)15\({}^{\circ}\) \& desktop display & 223.473 s \\ Camera rotation \& Contrast ratio & \(-\)15\({}^{\circ}\) \& 1.5:1 & 155.049 s \\ Shadows \& Display device & shadows off \& desktop display & 184.162 s \\ Shadows \& Contrast ratio & shadows off \& 1.5:1 & 145.195 s \\ Display device \& Contrast ratio & desktop display \& 1.5:1 & 138.634 s \\ \hline \end{tabular}
\end{table} 
Table 1: The investigated pairs, their intercept values, estimates, and standard errors. Next, the interactions between all pairs of factors were assessed. To conserve space, only the significant interactions are shown in Table 2. Inside the \"Estimate\" column, the estimates of the Intercept variables are presented between brackets, respectively. The data presented in Table 2 shows that the pair of FoV and camera rotation has the largest number of significant interactions: there are seven of them. Contrarily, the pairs of FoV & Display device; Camera rotation & Display device; Camera rotation & Contrast ratio; and lastly, Contrast ratio & Display device have only one significant interaction in them. The largest increase can be found in the case of 75\({}^{\circ}\) FoV and 0\({}^{\circ}\) camera rotation, while the largest decrease exists in the case of 90\({}^{\circ}\) FoV & 7:1 Contrast ratio with an estimate of 149.376 s. It can also be observed in Table 2 that when the camera rotation is paired with an undefined FoV, the estimates of interactions significantly decrease. A similar phenomenon happens when it is paired with the Gear VR. Also, pairs that do not have interactions exist in the model. These are the following: FoV & Shadows; Camera rotation & Shadows; Display device & Shadows; and lastly, Contrast ratio & Shadows. This means that every pair that has the factor of shadows in them, do not have significant interactions.