I think e I don't think non vengono mai usati da soli, ma vengono sempre seguiti da so, come nell'esempio, o da una proposizione come nel caso di I think/I don't think he went to the concert.
In addition to Italian, the official language, Italy has a host of dialects, which are used primarily in speaking rather than in writing. Dialects vary from region to region and even within a region. Italian itself is based on the dialect of Tuscany.