I trust that this also can be done with experts' input. Data-intensive techniques are not necessary here.

to ensure though the big data use appropriately the below mentioned points for data interoperability and GDPR to foster data economy and not being a barrier are very important. Also we need to research more on the wish of several stakeholders to Move to an Open Data Landscape with Open data being necessary for the offerings of new services or to generate research

I kind of agree with the first comment here...

The identification of key stakeholders and their role in the policymaking process should ideally be done in parallel with the analysis of big data, and not necessarily afterwards.