Amanda Knox: post mortem

Con­tin­u­ing my in­ter­est in track­ing real-world pre­dic­tions, I no­tice that the re­cent ac­quit­tal of Knox & Sol­lecito offers an in­ter­est­ing op­por­tu­nity—speci­fi­cally, many LessWrongers gave prob­a­bil­ities for guilt back in 2009 in kom­pon­isto’s 2 ar­ti­cles:

Both were in­ter­est­ing ex­er­cises, and it’s time to do a fol­lowup. Speci­fi­cally, there are at least 3 new pieces of ev­i­dence to con­sider:

  1. the failure of any damn­ing or es­pe­cially rele­vant ev­i­dence to sur­face in the ~2 years since (see also: the hope func­tion)

  2. the in­de­pen­dent ex­perts’ re­port on the DNA evidence

  3. the free­ing of Knox & Sol­lecito, and con­tinued im­pris­on­ment of Rudy Guede (with re­duced sen­tence)

Point 2 par­tic­u­larly struck me (the press at­tributes much of the ac­quit­tal to the ex­pert re­port, an ac­quit­tal I had not ex­pected to suc­ceed), but other peo­ple may find the other 2 points or un­men­tioned news more weighty.

2 Probabilities

I was cu­ri­ous how the con­sen­sus has changed, and so, in some spare time, I sum­moned all the Con­scien­tious­ness I could and com­piled the fol­low­ing list of 54 en­tries based on those 2 ar­ti­cles’ com­ments (some­times in­fer­ring spe­cific prob­a­bil­ities and pos­si­bly miss­ing prob­a­bil­ities given in hid­den sub­threads), where peo­ple listed prob­a­bil­ities for Knox’s guilt, Sol­lecito’s guilt, and Guede’s guilt:

Knox Sol­lecito Guede LWer
.20 .20 .70 bad­ger
.05 .10 .90 mat­tnew­port
.20 .25 .90 An­gryParsley
.05 .05 .95 tut
.05 .05 .95 ben­tarm
.85 .60 .20 bgrah449
.01 .01 .99 ko­dos96
.01 .01 .99 Daniel_Bur­foot
.40 .40 .90 nerzhin
.45 .45 .60 Matt_Simp­son
.33 .33 .90 Cyan
.50 .50 .95 jimmy
.05 .05 .99 Psy­chohis­to­rian
.40 .40 .90 Threads
.50 .50 .80 Morendil
.15 Eliezer_Yud­kowsky
.20 .35 .98 Lau­raABJ
.10 .10 .90 cu­ri­ous
.20 .20 .96 jpet
.06 .06 .70 saliency
.80 .60 .95 Mario
.20 .20 .95 Yvain
.70 Shal­manese
.05 .05 .95 ge­lisam
.05 .05 .90 Mononofu
.90 .90 .90 lord­weiner27 (changed mind)
.50 .50 .99 GreenRoot
.99 .99 .99 di­lau­did
.13 .15 .97 Jack
.05 .05 .90 wedrifid
.01 .01 .90 Nanani
.35 .35 .95 imaxwell
.01 .01 .99 jen­marie
.25 .25 .75 Jawaka
.41 .38 .99 magfrump
.40 .20 .60 gw­ern
.08 .10 .95 loqi
.25 .25 .50 JamesAn­drix
.90 .85 .99 Un­knowns
.35 .35 .90 Se­bas­tian_Ha­gen
.90 .90 .99 brazil84
.30 .30 .40 ChrisHib­bert
.02 .02 .98 wnoise
.50 .40 .90 John_Maxwell_IV
.10 .10 k3nt
.01 .01 .99 Si­nai
.00 .00 1.0 KayPea
.00 .00 .60 Mer­leRide­out
.15 .10 .80 TheRev
.01 .01 .99 kom­pon­isto
.30 pete22
.01 SforSin­gu­lar­ity
.00 .00 .90 An­naGil­mour
.05 .05 .95 Seth_Goldin
.60 .60 .95 big­jeff5

It’s in­ter­est­ing how many peo­ple as­sign a high-prob­a­bil­ity to Knox be­ing guilty; I had re­mem­bered LW as be­ing a hive of Amanda fans, but ei­ther I’m suc­cumb­ing to hind­sight bias or peo­ple up­dated sig­nifi­cantly af­ter those ar­ti­cles. (For ex­am­ple, Eliezer says .15 is too high, but doesn’t seem oth­er­wise es­pe­cially con­vinced; and later one reads in Meth­ods of Ra­tion­al­ity that “[Ha­grid] is the most blatantly in­no­cent by­stan­der to be con­victed by the mag­i­cal Bri­tish le­gal sys­tem since Grindelwald’s Con­fund­ing of Neville Cham­ber­lain was pinned on Amanda Knox.”)

EDIT: Jack graphed the prob­a­bil­ity against karma:

2.1 Outliers

If we look just at >41% (cho­sen to keep con­tacts man­age­able), we find 12 en­tries out of 54:

Knox Sol­lecito Guede LWer
.45 .45 .60 Matt_Simp­son
.50 .40 .90 John_Maxwell_IV
.50 .50 .80 Morendil
.50 .50 .95 jimmy
.50 .50 .99 GreenRoot
.60 .60 .95 big­jeff5
.70 Shal­manese
.80 .60 .95 Mario
.85 .60 .20 bgrah449
.90 .85 .99 Un­knowns
.90 .90 .90 lord­weiner27
.90 .90 .99 brazil84
.99 .99 .99 di­lau­did

I have mes­saged each of them, ask­ing them to com­ment here, de­scribing if and how they have since up­dated, and any other thoughts they might have. (I have also mes­saged the first 12 com­menters or so, chronolog­i­cally, with <41% con­fi­dence in Knox’s guilt, with the same mes­sage.) The com­menters:

An­gryParsley /​ Cyan /​ Daniel_Bur­foot /​ Eliezer_Yud­kowsky /​ GreenRoot /​ John_Maxwell_IV /​ Lau­raABJ /​ Mario /​ Matt_Simp­son /​ Morendil /​ Psy­chohis­to­rian /​ Shal­manese /​ Threads /​ Un­knowns /​ bad­ger /​ ben­tarm /​ bgrah449 /​ big­jeff5 /​ brazil84 /​ di­lau­did /​ jimmy /​ ko­dos96 /​ lord­weiner27 /​ mat­tnew­port /​ nerzhin /​ tut

I look for­ward to see­ing their ret­ro­spec­tives, or in­deed, any­one’s ret­ro­spec­tives on the mat­ter.

All­know­ing and most mer­ciful Bayes;
We have erred, and strayed from thy ways like bi­ased sheep.
We have fol­lowed too much the de­vices and de­sires of our own hearts.
We have offended against thy ax­io­matic laws.
We have left un­done those up­dates which we ought to have done;
And we have done those up­dates which we ought not to have done;
And there is no cal­ibra­tion in us.
But thou, O Bayes, have mercy upon us, mis­er­able wannabes.
Spare thou them, O Bayes, who con­fess their faults.