Whoever wrote this began thus:
with a capital, rather than lower-case, initial P, as if this were named after two people named "Poly" and "Weibull". Consequently I almost reflexively moved the article to Poly–Weibull distribution, with an endash rather than a hyphen. Then I realized what "poly" meant and changed the "p" to lower case, and moved it again. The title now has a hyphen, not an endash.