Before revision: Even though this approach didn't manage to cover all people inside Twitter, it has several advantages over ordinary surveys that cover a smaller scale of groups: it is systematic, it is non-intrusive and it easily produces large volumes of rich data.
After revision: Even though this approach did not manage to cover all people inside Twitter, it has several advantages over ordinary surveys that cover a smaller scale of groups: it is systematic, it is non-intrusive and it easily produces large volumes of rich data.