This page makes no sense to the non-mathematician. Someone should clean it up and make it easier to read. Also, wouldn't a parabola count? 216.165.95.5 06:56, 3
| The content of the Unimodal function page was merged into Unimodal. For the contribution history and old versions of the merged article, please see its history. |
This page makes no sense to the non-mathematician. Someone should clean it up and make it easier to read. Also, wouldn't a parabola count? 216.165.95.5 06:56, 3 October 2007 (UTC)
In probability and statistics, a "unimodal probability distribution" is a probability distribution whose probability density function is a unimodal function, or more generally, (...) (this allows for the possibility of a non-zero probability for x=m).
I don't understand. The second definition (more general) accepts P[x=m] > 0. This seems to imply that the first one does not. Then, as I understand it, the first definition only accepts as "unimodal probability distribution" a probability distribution whose pdf is a unimodal function of mode m, with P[x=m] = 0, that is, pdf(m)=0. Such a pdf can't be unimodal with mode m. And thus the first definition rejects every probability distribution of being unimodal and thus defines an empty concept...--OlivierMiR (talk) 18:19, 11 September 2008 (UTC)
Feller says that unimodal distribution is a distribution function that is convex up to the mode and concave beyond it. Thus it may have density taking maximal values on an interval (say uniform distribution on [0,1]). In this case all points in [0,1] are local maxima (or there aren't any, if we consider strict 'peaks' only). Therefore I suggest a more general definition of a unimodal function: a function whose local maxima make up an interval.
Moreover, it might be worth replacing '(this allows for the possibility of a non-zero probability for x=m)' with '(in this case the distribution may have density everywhere except, possibly, m; this allows for the possibility of a non-zero probability for x=m)'
Matumba (talk) 17:56, 17 March 2009 (UTC)
I removed Pascal's triangle as an example since it does not follow the strict definition given here. The definition talks about "monotonically increasing for x ≤ m and monotonically decreasing for x ≥ m". In Pascal's triangle it is "monotonically non-decreasing for x ≤ m and monotonically non-increasing for x ≥ m", that is, a value can repeat. Specifically, in the page Pascal's triangle one can see the 3rd line has 3 twice. The value is not increasing or decreasing. What one can do is add a weaker form for which it applies. I might do that, but I want to check first. For now I removed the misleading example. --Muhandes (talk) 17:27, 6 July 2010 (UTC)
Rather than try to rewrite both this page and unimodal distribution I wrote unimodal and redirected there. I hope this is better solution. If not you are free to revert. --Muhandes (talk) 18:15, 12 July 2010 (UTC)
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