[...] * Specifically, the large majority of big data, from the most common such as social media and search engines data to transactions at self-check out in hotels or supermarkets, are generated for different and specific purposes. They are not the design of a researcher that elicits their collection with in mind already an idea of a theoretical framework of reference and of an analytical strategy. Specifically regarding data from social media, they can be really challenging to clean and demand a lot of effort. What is more, the data elicited from social media could be biased.