[FRIAM] Screening off

[Frank Wimberly]

Here's an idea example of a conditional independence assertion:  grey hair
is independent of gender given age.

Note:  I am not saying that's true.

---
Frank C. Wimberly
140 Calle Ojo Feliz,
Santa Fe, NM 87505

505 670-9918
Santa Fe, NM

On Mon, Dec 6, 2021, 4:32 PM Frank Wimberly <wimberly3 at gmail.com> wrote:

> We need to get together with a whiteboard or paper.  The value of S at t1
> could be 190 cm if S is height and t1 is Nick Thompson.
>
> ---
> Frank C. Wimberly
> 140 Calle Ojo Feliz,
> Santa Fe, NM 87505
>
> 505 670-9918
> Santa Fe, NM
>
> On Mon, Dec 6, 2021, 4:23 PM <thompnickson2 at gmail.com> wrote:
>
>> Frank,  Thanks for sticking with me on this.
>>
>>
>>
>> My comment was not conceptual, merely algebraic:  Can
>>
>>
>>
>> Pr(R at t3 | I at t2) = Pr(R at t3 | I at t2 & S at t1).
>>
>>
>>
>> …be true if the value of S at t1.is anything other than one?
>>
>>
>>
>>
>>
>>
>>
>> n
>>
>> Nick Thompson
>>
>> ThompNickSon2 at gmail.com
>>
>> https://wordpress.clarku.edu/nthompson/
>>
>>
>>
>> *From:* Friam <friam-bounces at redfish.com> *On Behalf Of *Frank Wimberly
>> *Sent:* Monday, December 6, 2021 3:07 PM
>> *To:* The Friday Morning Applied Complexity Coffee Group <
>> friam at redfish.com>
>> *Subject:* Re: [FRIAM] Screening off
>>
>>
>>
>> The question isn't whether 1 has occurred but what is the value of 1
>> (it's a variable) and is the distribution of 3 is independent of that
>> observed value.
>>
>> ---
>> Frank C. Wimberly
>> 140 Calle Ojo Feliz,
>> Santa Fe, NM 87505
>>
>> 505 670-9918
>> Santa Fe, NM
>>
>>
>>
>> On Sat, Dec 4, 2021, 5:38 PM Nicholas Thompson <thompnickson2 at gmail.com>
>> wrote:
>>
>> Frank,
>>
>>
>>
>> Still need help. Given events 1, 2, and 3, 3 has been screen off by 2
>> from 1, if  the probability that 3 occurs given that 2 has occurred is
>> equal to the probability that 3 occurs given that both 2 and one have
>> occurred.     As I understand mathematics this equality requires that the
>> probability of 1 occurring is 1.00.  Another way to say that is that the
>> probability that 3 occurs  if 2 has occurred is the same as the probability
>> that 3 has occurred if 2 has occurred, and 1 has already occurred.  What's
>> the fun in that?  In other words, given the possibility of other causes for
>> 2, the fact that 2 occurs gives us relatively little evidence that 1 has
>> occurred.  Isn"t this true of all causal abduction?
>>
>>
>>
>> N
>>
>>
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>
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