What is analysed by the Metadata Quality Assurance tool?

The datasets stored in the portal need to be of an appropriate quality in terms of: 

• DCAT-AP-compliant mapping
• Available distributions
• Usage of machine-readable distribution formats
• Usage of known open-source licences.

To check the datasets for these quality indicators the Metadata Quality Assurance (MQA) tool was developed. The MQA runs as a periodic process in parallel to the harvesting. CKAN and Virtuoso are filled with metadata through the harvesting process. As CKAN cannot store DCAT-AP-formatted datasets directly, the datasets are mapped into a JSON (JavaScript Object Notation) schema that is DCAT-AP compliant. The MQA uses this schema for checking each dataset for its DCAT-AP mapping compliance. If there are any compliance issues detected, for instance if a mandatory field is missing, the dataset is considered as not DCAT-AP compliant. 

The MQA presents its results in two views. 

• The landing page or ‘Global Dashboard’. This view shows aggregated results for the entire service, i.e. the quality details for all catalogues.
• The second view or ‘Catalogue Dashboard’. This view allows you to select a specific catalogue for which you want to display the quality details.

The current quality indicators include the following. 

1. Distribution statistics: 

   1. accessible distributions
   2. error status codes
   3. download URL
   4. existence, 
   5. top 20 catalogues with most accessible distributions, 
   6. ratio of machine-readable datasets, 
   7. most-used distribution formats, 
   8. top 20 catalogues mostly using common machine-readable datasets. 
2. Dataset compliance statistics:
   1. top violation occurrences, 
   2. compliant datasets, 
   3. top 20 catalogues with most DCAT-AP-compliant datasets. 
3. Dataset licence usage: 
   1. ratio of known to unknown licences, 
   2. most used licences, 
   3. top 20 catalogues with most datasets with known licences.