For example, what are your chances of getting admitted to the "most selective" colleges? Let's say Stanford, Duke, Swarthmore, Northwestern, the Ivies or the like - that type, which often garner the "most selective" label from guide books. One way to approach the question is to look at the recent Rate of Admission.
Stanford, for instance had nearly 44,000 applications in 2016. They admitted at a rate of 4.7%. In 2015, they admitted at a rate of 5.0%, indicating that the range seems fairly consistent from year to year. Indeed, they are "most selective".
A few other colleges also hovered around the 5% or 6% Admit Rate in 2016: Harvard at 5.2, Yale and Columbia at 6.
In the 7-9% range were Princeton 7, MIT 8, Brown and Penn 9.
Other examples of respected colleges ranged higher, such as, Dartmouth, Duke, and Northwestern at 11, Johns Hopkins at 12, Swarthmore at 13, Cornell at 14, Georgetown at 16, Williams at 17.
This is by no means an exhaustive list of "most Selective" colleges, and in most cases the Admit Rates are approximate and not broken down to decimal level. It does present, however, one statistical view of the relative degree of difficulty of admission.
Be reminded that these numbers do NOT predict who will get an "admit" and who will get a "reject" - each application stands on its own. A prospective applicant is an "individual", who will present a unique and current profile and who should not be persuaded or dissuaded from applying based on the rates of past "groups".
Though stats are important, they should not be the decisive factor for applying or not applying to any particular college. Your chances of getting in are unique to you and your application and the needs or wants of the college this year. Though we may be able to predict an Admit Rate, there is no predicting who will get in. You may have just what they are looking for, If you like a college and want to attend, by all means you should apply, regardless of what the stats say.