According to the 2016 US Presidential Candidates wiki page, there are eight potential candidates that have not formally announced their candidacy but have formed either an exploratory committee, a PAC, or a 527 organization.
I took to Google to learn more about these exploratory committees et al. They basically seem like a way to raise funds and explore/promote public interest in the candidate, and are a relatively recent practice. But what I haven’t been able to find are any statistics showing how frequently a person who forms this committee goes on to publicly announce a candidacy. Does anyone else have any statistics? Or, if someone has been following presidential elections for a few cycles, could someone offer any insight as to what the likelihood is? Thanks!