# Easing DApp Interaction for Non-Blockchain Users from a Conceptual Modelling Approach
## 7 Evaluation
### Results  
After manually recording the participants' questionnaires, which were received in the form of photos, we obtained the results shown in Tables 5 and 6. In the following, such results will be analyzed.  
As it can be seen in Table 6 and Figure 8, the clockchain version with middleware obtained better results for usability regardless of the company the subjects belonged to. These results were computed as the average score for all the questionnaire questions. Hence, the middleware version would be classified as SUS-grade A whereas the no-middleware one would obtain an F.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Company** & **Version** & **Average SUS Score** & **Average Elapsed Time** \\ \hline \multirow{2}{*}{A} & Middleware & 80.00 & 73.14 s. \\  & No Middleware & 34.58 & 168.04 s. \\ \hline \multirow{2}{*}{B} & Middleware & 81.61 & 75.65 s. \\  & No Middleware & 33.57 & 157.54 s. \\ \hline \multirow{2}{*}{C} & Middleware & 79.80 & 73.37 s. \\  & No Middleware & 34.02 & 157.80 s. \\ \hline \multirow{2}{*}{All} & Middleware & 79.93 & 72.57 s. \\  & No Middleware & 34.02 & 158.64 s. \\ \hline \hline \end{tabular}
\end{table}
Table 6: Experiment Results per Clockchain Version.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & & & \\ \hline \multirow{4}{*}{A} & \multirow{4}{*}{1} & Middleware & 8.8 & 8.8 & 8.1 & 6.3 & 6.3 & 9.4 & 9.4 & 7.5 & 6.9 \\  & & 4 & No Middleware & 4.4 & 0 & 6.3 & 4.4 & 1.9 & 8.1 & 2.5 & 5.6 & 1.3 & 1.3 \\ \cline{2-13}  & & & No Middleware & 5.8 & 2.5 & 4.2 & 5 & 0.8 & 7.5 & 0.8 & 3.3 & 3.3 & 0 \\  & & 4 & Middleware & 6.7 & 7.5 & 9.2 & 8.3 & 7.5 & 9.2 & 8.3 & 6.7 & 7.5 & 9.2 \\ \hline \multirow{4}{*}{B} & \multirow{4}{*}{1} & \multirow{4}{*}{7} & Middleware & 8.4 & 10 & 9.7 & 6.9 & 6.6 & 7.5 & 8.4 & 9.4 & 7.2 & 7.2 \\  & & 4 & No Middleware & 3.8 & 0.6 & 6.6 & 5 & 3.1 & 6.9 & 0.3 & 3.8 & 2.5 & 1.3 \\ \cline{2-13}  & & & No Middleware & 5.4 & 1.3 & 5.4 & 5 & 2.5 & 4.2 & 2.5 & 2.1 & 4.2 & 0 To accept or reject the null hypothesis H0A, a 2-Sample t Test was performed with an alpha of 0.05. Thanks to this test, we could conclude that the means for usability differ at the 0.05 level of significance, with a \(p\)-value of \(1.93\times 10^{-48}\). Therefore, with a 95% confidence level, that we rejected the null hypothesis H0A, meaning that the version of Clockchain with the implemented middleware does not have the same score for usability.  
Moreover, t Test requires that those data follow a normal distribution. With this aim we performed normality tests for the results for SUS score of both Clockchain versions, considering as null hypotheses the normality of both series of data. It was obtained a \(p\)-value of 0.63 for the middleware version and 0.59 for the no-middle version. Therefore, the normality of our data is confirmed. This fact is also represented in the histograms shown on Figure 9.  
Finally, despite not being the main focus of the experiment, it is worth noting the difference on the time the participants took to complete the experimental tasks depending on the Clockchain version they used (see Figure 10). Therefore, not only is the Clockchain version with middleware more usable, but it can also reduce task performance time.  
Figure 8: Usability results.  
Figure 9: Histogram for the system usability scale (SUS) score of Clockchain (**a**) with middleware and (**b**) without middleware.