# A Comparative Study of the Availability of Electric Buses in the Public Transport System
## 3 Experimental Procedure
### The Results of the Study  
The results of the K\({}_{\rm G}\)(t) availability tests are presented in the form of graphs in Figure 3 and in numerical form in Table 2. The graphs presented in Figure 3 illustrate the values averaged over each month of operation of the vehicle sample and the 3-month moving average of the K\({}_{\rm G}\)(t) index values. Figure 2: Bus technical readiness report, January 2022. An analysis of the data in the column chart shows a higher level of K\({}_{\rm G}\)(t) indexes for electric vehicles in each of the observed monthly periods. Higher K\({}_{\rm G}\)(t) technical availability of diesel vehicles was only observed in the 1 st, 2 nd, and 11 th months. The mean technical availability, K\({}_{\rm G}\)(t), of diesel vehicles for the whole observation period was K\({}_{\rm G}\)(t) = 0.79 with a standard deviation of S(K\({}_{\rm G}\)) = 0.08. For electric vehicles, the mean statistic was K\({}_{\rm G}\)(t) = 0.89 with a standard deviation of S(K\({}_{\rm G}\)) = 0.12. When comparing the median, similar values were found for K\({}_{\rm G}\)(t) = 0.80 and K\({}_{\rm G}\)(t) = 0.92 for diesel and electric vehicles, respectively. The lowest availability value for electric buses, K\({}_{\rm G}\)(t) = 0.28, was recorded in 1 month of operation. The lowest availability of diesel buses, K\({}_{\rm G}\)(t) = 0.58, was recorded in the 15 th month of operation. A graphical illustration of technical availability is shown in the box-and-whisker figures. Figure 4 shows the results for the whole observation period, and Figure 5 shows the results for the 'drive type' and 'operating period' groups. An analysis of the box-whisker plots indicates that there are outlier observations. Further analysis and calculations were carried out excluding these observations. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Statistics**} & \multicolumn{4}{c}{**Diesel**} & \multicolumn{4}{c}{**Electric**} \\ \cline{2-9}  & **33 Months** & **1 st Year** & **2 nd Year** & **3 rd Year** & **33 Months** & **1 st Year** & **2 nd Year** & **3 rd Year** \\ \hline Average & 0.79 & 0.85 & 0.74 & 0.78 & 0.89 & 0.86 & 0.92 & 0.90 \\ Median & 0.80 & 0.87 & 0.74 & 0.78 & 0.92 & 0.92 & 0.92 & 0.92 \\ Variation & 0.01 & 0.00 & 0.01 & 0.00 & 0.02 & 0.04 & 0.00 & 0.00 \\ Std. deviation & 0.08 & 0.06 & 0.07 & 0.05 & 0.12 & 0.19 & 0.04 & 0.04 \\ Minimum & 0.58 & 0.71 & 0.58 & 0.71 & 0.28 & 0.28 & 0.85 & 0.83 \\ Maximum & 0.90 & 0.90 & 0.83 & 0.86 & 0.99 & 0.99 & 0.98 & 0.94 \\ Interquartile & 0.32 & 0.19 & 0.25 & 0.15 & 0.71 & 0.71 & 0.13 & 0.11 \\ range & & & & & & & & \\ Coefficient of & 0.14 & 0.08 & 0.10 & 0.08 & 0.09 & 0.14 & 0.06 & 0.07 \\ variation [\%] & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Descriptive statistics of technical availability. Figure 3: Technical availability, K\({}_{\rm G}\)(t), of diesel and electric buses and 3-month moving average as function of monthly operating period, t.  
The condition of independence of observations, required for a univariate analysis of variance, was considered to be met. It was assumed that there are no latent relationships between observations. The measurability condition was also assumed to be met, as technical availability, K\({}_{\text{G}}\)(t), as the dependent variable is considered on a quantitative scale. The normality of the distribution in the analysed groups-'drive type' and 'operating period'--was verified using the Kolmogorov-Smirnov and Shapiro-Wilk tests (Table 3). For all analysed types of 'operating period' and 'drive type', the null hypothesis of normality of distribution was fulfilled in at least one verification test. Ambiguous results from both tests were only obtained for diesel vehicles at the 1 st year of operation, and for electric vehicles, at the 2 nd and 3 rd years of operation. Of the aforementioned groups, the normality condition of the distribution (\(p>\alpha=0.05\)) was only met by one of the two tests.