Witnesses had quite wide range on their estimations about Z age
Mageau: 26-30
Berryessa phone call/dispatcher (voice): early 20s (lets say 20-23)
Hartnell (eyewitness/voice): 20-30
First wanted poster after Stine murder: 25-30
Second wanted poster: 35-45
Nancy Slover (voice): mid 30s (lets say 35)
Stalker at Berryessa, maybe Zodiac
Three girls: 28
Couple on beach: 40
How can we separate ”good” estimations from ”bad” ones? Lets check what ”wisdom of the crowd” gives us. Here is couple of quotes about that concept:
if you take the independent best guesses from a large group of people such that their guesses aren’t influenced by “expert opinions” then the overall average tends to be the most accurate guess, even outperforming any of the individual experts within the group.
At a 1906 country fair in Plymouth, 800 people participated in a contest to estimate the weight of a slaughtered and dressed ox. Statistician Francis Galton observed that the median guess, 1207 pounds, was accurate within 1% of the true weight of 1198 pounds.
Now we can calculate avarage from witness estimations:
(26+30+20+23+20+30+25+30+35+45+35+28+40)/13 = 29,8
By the wisdom of crowd, Zodiac’s age was 29-30 at autumn 1969
Any thoughts?
Maybe. As it seems to be with all things Zodiac.
My new favourite suspect (Cragle’s) was 33-34 in 68.
Cool but perhaps we should reduce each witness "group" to one age number?
Mageau: 28 Berryessa phone call/dispatcher (voice): 22.5 Hartnell (eyewitness/voice): 25 First wanted poster after Stine murder: 27.5 Second wanted poster: 40 Nancy Slover (voice): 35 Three girls: 28 Couple on beach: 40
Then the average is 30.75.
The sample size (the people who saw Zodiac) is really really small, which makes it so much harder to make conclusions in any direction. However, personally I too, would probably consider an average of the opinions to be the most reliable estimation.
The other bad thing is that people age differently. Some people look much older than their age, some look much younger than their real age.
Not only is it a small sample size, we’re not even sure that everyone was looking at the same "ox".
