Charnin’s methods of calculating PN (joint probability) and PS are flawed, for several reasons.
Given the 500-word limit you’ve imposed, I’ll point out just one flaw. It has to do with the proposition the probability a witness was correct in hearing a shot from the grassy knoll was 0.42.
By way of perspective, it is true the probability of drawing a Queen from a deck of 52 is 4/52, or 1/13, or 0.0769. Note that here we know there are four Queens in the deck.
Charnin posits 51 witnesses said they heard grassy knoll shots; 32 witnesses said they heard TSBD shots; and 38 heard shots but had no opinion of their origin. This information is no basis whatsoever for saying there is 0.42 probability the 51 witnesses were correct — for saying there is 0.42 probability a shot came from the grassy knoll. All one can say from this information is that 42 percent of the witnesses said a shot came from the grassy knoll. That is ALL the information we can glean. We cannot by any logic bootstrap “42 percent of the witnesses said they heard a shot from the grassy knoll” into “there is a 0.42 probability a shot came from the grassy knoll.” The 51 witnesses could all be correct or incorrect; some could be daffy or deceitful; some could be swayed by another’s opinion. We don’t know.
The 51 witnesses are like the four Queens in the deck of 52. We know the probability of picking one of those witnesses out of the group of 121 total witnesses (probability = 0.42). But that’s all we know from the law of probability.
I guess I’ve got room to address Charnin’s calculations of PN and PS. The calculations make no sense whatsoever inasmuch as they’re based on the flawed notion that there was a 0.42 probability of a grassy knoll shooter.
A case of garbage in, garbage out.”