# Talk:Dispersity

WikiProject Polymers
Dispersity is within the scope of WikiProject Polymers which aims to improve the coverage of polymer-related articles in Wikipedia. If you are interested, you may visit the project page and join with us. Feel free to leave messages at the project talk page.

I think the the author has got the number avg and the weight avg backwards. it's numb avg / weight avg. not other way around.

It's weight average / number average. PDI is always larger than 1.
${\displaystyle {\bar {M}}_{w}={\frac {\sum _{i}N_{i}M_{i}^{2}}{\sum _{i}N_{i}M_{i}}}}$ and ${\displaystyle {\bar {M}}_{n}={\frac {\sum _{i}N_{i}M_{i}}{\sum _{i}N_{i}}}}$.
Nathaniel 06:19, 15 December 2005 (UTC)

## Polydispersity vs "Dispersity"

The main issue with this edit is that the "new terminology" isn't used by actual researchers. It's a little silly to "retire" the commonly used meaning, when the "new" term isn't used by anyone other than IUPAC. (+)H3N-Protein\Chemist-CO2(-) 15:09, 8 March 2014 (UTC)

Except that (a) it is used and (b) documentation should show what is preferred and correct. — Preceding unsigned comment added by 193.49.43.127 (talk) 17:40, 9 December 2014 (UTC)
It's not as if I'm proposing moving this article back to polydispersity. It's just that having "formerly described as monodisperse" showing up all over the place (not just in this specific article) was kind of unnecessary, since it is still the more commonly used term in the literature, for now at least. And as far as correctness goes, it's not as if the implied physiochemical meanings of Dispersity and Polydispersity are actually different, from a scientific standpoint they're equally correct. Dispersity has gained quite a bit of ground in the last year though, at least in terms of frequency of use in recent publications, so it's not as clear cut as it was when I made the above statement last March. (+)H3N-Protein\Chemist-CO2(-) 22:42, 10 December 2014 (UTC)
For reference, this was my edit. I didn't remove the IUPAC terminology at all. (+)H3N-Protein\Chemist-CO2(-) 22:46, 10 December 2014 (UTC)
I disagree with user:Protein Chemist regarding researchers not using the term dispersity. While there is indubitably inertia in the community, the IUPAC nomenclature is picked up by more and more colleagues and, in my opinion, mainly older colleagues stick to polydispersity. Robert Luxenhofer, October 28th 2015