# An Integrated Decision Support Model for Evaluating Public Transport Quality
## 3 Results and Discussion
### Sensitivity Analysis  
The final priorities of the alternatives rely highly on the weights linked to the main criteria. Minor changes within the relative weights can, therefore, cause major changes in the final ranking. Since these weights are usually based on highly subjective evaluation and judgments, the stableness of the ranking under varying criteria weights needs to be tested. For this purpose, sensitivity analysis can be performed based on scenarios that reflect alternative future developments or different views on the relative importance of the criteria [41]. Through increasing or decreasing the weight of individual criteria, the resulting changes within the priorities and thus the ranking of the alternatives are often observed. Sensitivity analysis, therefore, provides information on the stableness of the ranking. If the ranking is extremely sensitive to small changes within the standard weights, a careful review of the weights is usually recommended. In addition to this, decision criteria should be included as a sensitive ranking point to a weak discrimination potential for this set of criteria.  
For this purpose, the weights of the important criteria are separately altered, simulating weights between 0% and 100%.  
Performance sensitivity of alternatives was analyzed for the three decision groups. For the passengers' group (see Table 10), when \"Transport quality\" was increased from 0.3559 to 0.36, this change did not affect the first level and each criterion kept its same position, while a change was detected in the second level. \"Physical comfort\" moved to the fifth position in place of the \"Info before travel\" criterion, while in the third level, the \"Safety of stops\" criterion fell to the seventh position instead of \"Comfort of stops\", which means that minor changes were detected for the passengers' group.  
For the public transport expert group, the change of scores is very minor in the first level and did not change the position of the criteria, but in level 2 some changes were observed due to the sensitivity analysis check. The \"Info before travel\" attribute moved to the first position for this minor change and \"Time availability\" improved its ranking by moving to the seventh position. Thus, level 2 was found to be sensitive (shown in Table 11). \"Physical comfort\" and \"Mental comfort\" both fell by one position.  
Figure 5: The subfactors ranks based on the different group preferences on the third level.  
In level 3, the attributes proved to be stable in their rankings, especially for the first five positions, while the ranking was otherwise changed, as shown in Table 11.  
For the municipal officials group, interestingly, the change had an effect on the score positions for criteria when the weight of the \"Transport Quality\" criterion was changed from 0.3473 to 0.3500. The ranking was changed in the first level; \"Fare\" moved to the third position instead of \"Tractability\", but in level 2 some changes were observed due to the sensitivity analysis check. The \"Directness\" attribute moved to the first position for this minor change, and \"Safety of travel\" moved to the second position. Hence, level 2 was found to be sensitive, as shown in Table 12. Level 3 was affected by the sensitivity check, but \"Fit connection\" proved to be stable even when the sensitivity check was conducted, and kept its first position in this level. Nevertheless, the \"Need of transfer\" criterion rose to the second position from its previous fourth position (Table 12).