# Talk:Pointwise mutual information

If the measure is symmetric, then why is the higher bound said to be -log(p(x))? That does not make any sense. ("The measure is symmetric (SI(x,y) = SI(y,x).) It is zero if X and Y are independent, and equal to -log(p(x)) if X and Y are perfectly associated. Finally, SI(x,y) will increase if p(x|y) is fixed, but p(x) decreases.") It implies that SI(x,y) would be bounded from 0 to -log(p(x)) but SI(y,x) from 0 to -log(p(y)) but both values would be equal. Sense, this does not make. pfl (talk) 11:50, 18 July 2008 (UTC)

If x and y are "perfectly associated", then they always have the same value. So -log(p(x)) = -log(p(y)) and the bounds are the same. —Preceding unsigned comment added by 140.32.16.100 (talk) 00:22, 5 November 2008 (UTC)

There is no range for PMI other than -infinity to infinity. An example has been added which shows this. Bazugb07 (talk) 20:54, 6 February 2009 (UTC)

Why is the equation named "SI()" when the article is called "Pointwise Mutual Information"? It should at least be explained if it refers to "Specific MI"...Skywise 78 (talk) 14:58, 17 March 2009 (UTC)

There seems to be a typo. It should be

```
\operatorname{pmi}(x;yz) = \operatorname{pmi}(x;y) + \operatorname{pmi}(x; z|y) instead of
\operatorname{pmi}(x;yz) = \operatorname{pmi}(x;y) + \operatorname{pmi}(x; y|z) ??? — Preceding unsigned comment added by 128.174.241.42 (talk) 20:35, 25 May 2013 (UTC)
```

## Event vs outcome[edit]

Pretty sure the intro should use the word "outcomes" rather than "events"? The section under the table of contents seems to use the correct language. 203.63.183.112 (talk) 01:14, 24 January 2018 (UTC)