I just want to say that in my case, I believe I am getting into better PhD programs now (currently in a terminal MA program, graduating in May) than I would have had I applied last year (w/o MA).
(Note: Statistics may be different in this regard, since it's not uncommon for first year PhD students to already have a masters.)
I made the choice to not apply for PhD last year (and to apply for MA instead) for multiple reasons: (1) my undergrad is fairly unknown, so having an MA from a well known institution might help the application, (1a) I had good grades as an undergrad, but because its a lesser known school, adcomms may not know how rigorous the classes are. Thus, having strong grades from a well known institution reinforces that my GPA was not a result of easy classes; (2) many statistics jobs are available for someone with a masters so it is certainly not a waste if I got rejected from all PhDs, (2a) it is only a one year program, so I am not spending too huge of an amount; (3) it affirms for myself (and adcomms) that this is truly what I want to be studying; (4) I've been able to add to my CV, and gain access to more "famous" recommenders; and (5) my SO is at this school, so we get a full year of being in the same place before spending four years long distance.
While reason (5) was originally my main reason, the others are all true (and are how I managed to justify it to myself). Because I didn't apply for PhDs last year, I cannot say definitively that I did better this year than I would have without the MA. However, I honestly cannot imagine that I would have gotten into these schools last year (my background was strong enough that I think I'd have gotten in places, just not the same caliber places).
Again, statistics may be different than other programs, and a masters (as others have stated, though I think we all knew this anyway) is not a guarantee. But I wanted to point out that in my case it really did help. Ie, in answer to your question, "Yes, it can help."