Cases study 1:
In the case study, we wonder whether the presence of a motorway affects the average net earnings?
- Through which municipality drives the motorway?
- Are the average monthly net earnings of the population in these municipalities lower or higher than the average of all municipalities?
We started the answer to this question by downloading data:
- Average monthly net earning - municipalities, 2017 (STAGE II)
- Public utility infrastructure layer - roads (e-Geodetic data)
After the transfer, we extend the data and import them into QGIS.
The next step is filtering the motorways from the public infrastructure layer. Governmental spatial data (and other data that follow standards such as ISO / TC 211) have objects defined by the identification codes. In the spatial data documentation, we can find an explanation of the codes and their description. After reviewing the description of the data, it was found that all motorway have a value 1 in the ATR1 column of the transferred layer.
We exported all motorways so that we opened the attribute table and with the help of the Expression tool 
we marked all the data that have the value 1 in the column ATR1.
We exported the highlighted motorways so that with the right click we came to the Save As option and marked Save only selected features when saving. After the motorway filtering, the situation is as follows:
In order to gain the municipalities over which the motorway network runs, we used the Join attrobutes by location tool. We defined the input layers and the geometric predicate - crossing.
We got the answer to the first question. In Slovenia, the motorway crosses 66 municipalities, which are listed in our attribute table.
The next step is to calculate the average monthly net earning of the population in these municipalities and compare it with the average of all municipalities.
The calculation was performed using the Expression tool.
According to our calculations, we can see that the average monthly net earning (municipalities, 2017) in Slovenia is € 954,28. In the municipalities across which the motorway crosses, it is 976,16 €. This means that in these municipalities the average annual earings in 2017 were 21,88 € higher. In this result, we must bear in mind that the north-eastern part of the motorway network travels across municipalities with a significantly higher deviation from the mean value. The standard deviation of the sample is € 94,10, while the standard deviation of all municipalities is € 86,01.
Based on the findings, it can be argued that the presence of a motorway may affect the average net earning.