Papers differing primarily by examined dataset, not analysis technique I am considering a specific topic in research paper within data mining field. I just found that my idea is being implemented and published in arXiv in the last month. So far, the published paper matches the flow that I was planning to follow but the author has considered the study with Twitter data. My question is: If I want to do the same experiments but with a different data set like facebook data set will it be considered a new contribution in that field ? 

Ps: Row data crawled from Twitter API is way different from row data crawled from Facebook API, and the also different in structure and body.
In fact, the main contributions in your field are "algorithms", however, data sets are just a bunch of inputs for testing those algorithms and assessing their functionality or efficiency. If the outcomes of your new tests with data set A are exactly the same as dataset B's ones, you might not claim it as a new contribution. But if the results acquired from dataset B lead to some different interpretations about your algorithm's computational capabilities or something, you can consider it as a new contribution.