Let’s say A=”Knox killed Kercher”, B=”Kercher has been killed and Knoxed lived in Italy and is an intelligent 20-year-old female college student with no criminal history”, C=”evidence against Guede”, D=”Knox and Kercher were roommates”, E=”evidence of a staged burglary”, F=”bra and clasp”, G=”all other information about the case”.
I’ll redefine slightly:
A := “Knox killed Kercher, given background info about both, but not the fact of their acquaintance”. P(A) = tiny.
B := “Kercher killed”. P(A|B) = approximately P(A). (We are not yet given that they were roommates.)
C := “evidence against Guede”. P(A|B&C) = approximately P(A). (No significant connection between Guede and Knox.)
D := “Knox and Kercher were roommates”. P(A|B&C&D) = slightly higher than P(A), but still well below the threshold of consideration.
E := “Facts cited as evidence of staged burglary”. P(A|B&C&D&E) = approximately P(A|B&C&D). (Likelihood ratios involved are close to unity; certainly small relative to P(~A)/P(A).)
F := “bra clasp and knife”. P(A|B&C&D&E&F) = possibly as much as an order of magnitude higher than P(A|B&C&D). (Explaining results is a minor puzzle.)
G := “all other information”. P(A|B&C&D&E&F&G) = approximately P(A|B&C&D&E&F). (Other evidence weak; slightly inculpatory facts canceled out by slightly exculpatory facts.)
Thanks, that’s very helpful. Perhaps you could copy this to the main debate branch, so Rolf would see it and possibly respond in a similar fashion? Also, to seek a bit more clarification, what is your estimate of P(A|B&C&D) / P(A|B&C)?
I’ll redefine slightly:
A := “Knox killed Kercher, given background info about both, but not the fact of their acquaintance”. P(A) = tiny.
B := “Kercher killed”. P(A|B) = approximately P(A). (We are not yet given that they were roommates.)
C := “evidence against Guede”. P(A|B&C) = approximately P(A). (No significant connection between Guede and Knox.)
D := “Knox and Kercher were roommates”. P(A|B&C&D) = slightly higher than P(A), but still well below the threshold of consideration.
E := “Facts cited as evidence of staged burglary”. P(A|B&C&D&E) = approximately P(A|B&C&D). (Likelihood ratios involved are close to unity; certainly small relative to P(~A)/P(A).)
F := “bra clasp and knife”. P(A|B&C&D&E&F) = possibly as much as an order of magnitude higher than P(A|B&C&D). (Explaining results is a minor puzzle.)
G := “all other information”. P(A|B&C&D&E&F&G) = approximately P(A|B&C&D&E&F). (Other evidence weak; slightly inculpatory facts canceled out by slightly exculpatory facts.)
Thanks, that’s very helpful. Perhaps you could copy this to the main debate branch, so Rolf would see it and possibly respond in a similar fashion? Also, to seek a bit more clarification, what is your estimate of P(A|B&C&D) / P(A|B&C)?