# Is this a valid inference?

**URL:** <https://boards.straightdope.com/t/is-this-a-valid-inference/618507>\
**Category:** In My Humble Opinion\
**Created:** [April 11, 2012, 11:25pm UTC](https://boards.straightdope.com/t/is-this-a-valid-inference/618507 "2012-04-11T23:25:11Z")\
**Posts on this page:** 3\
**Page:** 3

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**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\
**Post date:** [April 12, 2012, 4:52pm UTC](https://boards.straightdope.com/t/is-this-a-valid-inference/618507/41 "2012-04-12T16:52:03Z")

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> [@Heart\_of\_Dorkness](#):
>
> …“If you learn that someone is an organ player, does that make them more likely to be a vampire?” is a complete thought in and of itself.

That doesn’t read as a complete thought to me, but that doesn’t really guarantee that other people won’t read it that way. I’d edit in something clearer if I could, but for now I’ll just count it as a lesson learned.

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**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\
**Post date:** [April 12, 2012, 11:09pm UTC](https://boards.straightdope.com/t/is-this-a-valid-inference/618507/42 "2012-04-12T23:09:59Z")

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> [@MichaelEmouse](#):
>
> There are two possibilities I see:

I also see two interpretations, but one of them is different:

1. _If you learn that someone is an organ player, does that make them more likely to be a vampire than someone who doesn’t [play the organ]?_
2. _If you learn that someone is an organ player, does that make them more likely to be a vampire than someone who doesn’t [learn that someone is an organ player]?_

The first is P(V|O) \>? P(V|-O), while the second is P(V|O) \>? P(V).

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**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\
**Post date:** [April 13, 2012, 12:40am UTC](https://boards.straightdope.com/t/is-this-a-valid-inference/618507/43 "2012-04-13T00:40:05Z")

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nm

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