## 4 Evaluation of Technical Condition of Vehicles at the PTI
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **F-Test Two-Sample for Variances** & \\  & **Variable 1** & **Variable 2** \\ \hline Mean & 12.67635036 & 14.36952381 \\ Variance & 10.15508511 & 8.430314762 \\ Observations & 137 & 21 \\ df & 136 & 20 \\ F & 1.204591453 & \\ P(F \(\leq\) f) one-tail & 0.32628342 & \\ F Critical one-tail & 1.890238594 & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of F-Test for variances. The results of this test indicate that with a reliability of 95%, the zero hypothesis is accepted that the two groups of data have the same deviations (because the \(p\)-value is greater than 0.05). Based on the result of the F-Test, a \(t\)-Test was selected for comparison of averages, assuming the same deviations of the two groups of PTI data with and without the ISO standard. The result of this test is recorded in the Table 4.  
The results of the \(t\)-Test show that the \(p\) value (0.023) is less than 0.05. This means, with 95% reliability the average percentage of temporarily roadworthy and not roadworthy vehicles of all PTIs in the Slovak Republic in the period of 2019-2020 which are certified according to ISO 9001, and the average percentage of all PTIs without this certification, is significantly different and therefore hypothesis H1 is accepted. The Influence of the Introduction of Quality Management System on the Results of PTI in Selected Countries of the European Union  
Additionally, a survey was carried out on the pattern of eleven European Union countries (Austria, Germany, Poland, Estonia, Finland, Slovak Republic, the Czech Republic, Latvia, Sweden, Spain, and Ireland), whose authorities were willing to cooperate. For these countries the average results of the technical condition of the vehicles registered for PTI check in the given countries in 2019 were assessed and examined (temporarily roadworthy and not roadworthy vehicles for road traffic use) in relation to the obligation to introduce certification or accreditation according to the ISO standard at the PTI of the given country. The results are recorded in the table in Figure 2.  
The above inquiry found that in the six countries, in which the PTI achieved the highest level of assessment of the technical condition of vehicles as temporarily roadworthy and not roadworthy for road traffic use (Spain, Germany, Sweden, Finland, Ireland, and Latvia) it is mandatory for PTIs to be accredited or certified according to the ISO standard (most often it is ISO/IEC 17020). The significance of this difference can also be demonstrated by statistical research. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{\(t\)-Test Two-Sample Assuming Equal Variances} & \multicolumn{1}{c}{\multirow{2}{*}{**Variable 2**}} \\  & **Variable 1** & **Variable 2** \\ \hline Mean & 12.67635036 & 14.36952381 \\ Variance & 10.15508511 & 8.430314762 \\ Observations & 137 & 21 \\ Pooled Variance & 9.933960708 & \\ Hypothesized Mean Difference & 0 & \\ df & 156 & \\ T Stat & \(-\)2.292353641 & \\ P(T \(\leq\) t) one-tail & 0.011610975 & \\ t Critical one-tail & 1.654679996 & \\ P(T \(\leq\) t) two-tail & 0.02322195 & \\ t Critical two-tail & 1.975287508 & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: State comparison \(t\)-Test results. Based on the data shown in Figure 1 it is possible to establish the hypothesis (H1) that the difference between the average percentage of temporarily roadworthy and not roadworthy vehicles of all states in which PTIs are compulsorily accredited or certified according to ISO standard and states without this accreditation or certification, is significant against the hypothesis that this difference is not significant (Ho). So, for this reason, statistical research will be carried out in the form of tests, performed on these two groups of values in the Data Analysis application in MS Excel program.