Overwhelming evidence? It's probably a bad thing

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The old adage that says "If it sounds too good to be true, it probably is" has finally been put to the test – mathematically – in research led by the University of Adelaide.

In a new paper to be published in Proceedings of the Royal Society A, a team of researchers has found that without a dissenting opinion can in fact weaken the credibility of a case, or point to a failure of the system.

One of the examples cited by the research team is an ancient Jewish law that said a could not be convicted of a capital crime if all judges unanimously handed down a guilty verdict.

"It might sound counterintuitive to say that a unanimous verdict could be wrong, but this ancient law indicated that the system may be in error if there was complete agreement among the judiciary," says corresponding author Professor Derek Abbott, a probability expert from the University of Adelaide's School of Electrical & Electronic Engineering.

The team put three different scenarios to the test based on mathematical probability: the use of to confirm the identity of a criminal suspect; the accurate identification of an archaeological find; and the reliability of a cryptographic system.

They found in each case that there was a point at which "too much of a good thing" actually weakened confidence in the result.

"In our first example, we imagine there are 13 witnesses who all confidently identify a criminal suspect after seeing the suspect briefly. But getting a large group of unanimous witnesses in these circumstances is unlikely, according to the laws of probability. It's more likely the system itself is unreliable," says Professor Abbott.

"In our scenario, the that a suspect is guilty is strong after three positive identifications by witnesses. But our tests showed that the more positive confirmations you have beyond those three, the more it erodes our confidence that this is the right person being identified.

"The situation would be quite different if the witnesses had all been taken hostage for a month by the suspect. Then you would expect them all to agree very well who the kidnapper was.

"The ancient Jewish legal practice referred to in our work indicates a surprising level of intuitive sophistication for the time, when such statistical tools would not have been at their disposal. They knew that it was rare for everyone to agree," Professor Abbott says.


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Why too much evidence can be a bad thing

More information: Too good to be true: when overwhelming evidence fails to convince. arxiv.org/abs/1601.00900
Citation: Overwhelming evidence? It's probably a bad thing (2016, January 12) retrieved 20 June 2019 from https://phys.org/news/2016-01-overwhelming-evidence-bad.html
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Jan 12, 2016
Overwhelming evidence? It's probably a bad thing


"Overwhelming evidence" can also fall into a category of what can be labeled as "wishful thinking". There are those "groupie types" with consensus positions who can never be shaken from it no matter how weak the evidence for their position is. There are those who post here on a regular basis who believe when they look in a mirror that 80% of their body mass is "missing", when it is really just" wishfull thinking" on their part.

Jan 12, 2016
Overwhelming evidence? It's probably a bad thing

Didn't we just have this paper on here?
http://phys.org/n...bad.html

Can we just copy and paste the comment section from there and spare us the repeat?

Jan 12, 2016
Overwhelming evidence? It's probably a bad thing

Didn't we just have this paper on here?
http://phys.org/n...bad.html


......no, that is not what it was about, this is just "wishful thinking" on your part.

Jan 12, 2016
no, that is not what it was about, this is just "wishful thinking" on your part.

Erm...you do realize that the paper linked in this article and the one I cited are the same paper?

Jan 12, 2016
What the heck? Why are they reposting the exact same article from a few days ago?

Jan 12, 2016
What the heck? Why are they reposting the exact same article from a few days ago?


Clickbait.

A small percentage of reposted or pointless crap articles in the stream increases the amount of pagevisits that inflates the apparent volume of traffic on the site by tricking people into clicking the articles and then complaining about it, which makes the site appear more attractive to advertisers.

They've simply calculated how much empty content they can pass out without losing visitors.

Jan 12, 2016
V Sauce has a video about this law

Jan 14, 2016
I knew it- atoms definitely don't exist. We are a mix of Wind, fire and earth.

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