

Throwing dice gets to the truth about killing leopards  - ColinWright
http://www.newscientist.com/article/dn20746-throwing-dice-gets-to-the-truth-about-killing-leopards.html

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jonkelly
This reminds me of another technique I learned in a PoliSci class (too many
years ago). The prof had been polling people about sensitive topics like race.
His survey asked respondents only yes/no questions and asked them only to
listen to each question and privately write down yes or no to each question.
Then they were asked to count the yeses. By only asking 1/2 the survey group
the sensitive question, you get a measure of the true ratio for the sensitive
question. You end up doubling the sample size to get the same number of
responses, but you allow people to hide behind their other answers.

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Synthetase
I remember being taught this technique in my discrete math class last
semester. At first blush, it seemed utterly ridiculous. One could still infer
the result, the true signal.

It was only after some consideration from the human side I realized did I
begin to realize the psychological appeal. I can feel in my gut the
psychological appeal of hiding behind the throw of a dice but the mind still
rebels and the mere paper of plausible deniability it provides.

EDIT: I say this not because I misunderstand the technique mathematically.
Indeed, this was one of the more enjoyable topics covered. One could still
infer the probability an individual was telling the truth depending on the
strength of the fuzzing signal.

I am merely expressing my puzzlement at this quirk of psychology.

~~~
saurik
Because you aren't asking the same person the same question over and over
again, and in fact only have a single data point for each person, there is no
way to "infer the result, the true signal": the "plausible deniability" this
yields isn't just a psychological trick, but is actually mathematically sound;
in the end you can determine things about the population as a whole, but you
cannot determine who was forced to say "yes" and who volunteered a "yes".

~~~
saurik
I've gotten a sufficiently large number of upvotes from this comment that I
feel compelled to follow up after having gotten a (half) night's sleep: you
are asking the pollee multiple /different/ questions, and if there are
correpations between the answers (which the poller suspected to bd the case in
this article) you actually can deduce information about each individual sith
increasingly high probability ". If this what the person I responded to meant
by "true signal", then he is correct.

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Lewisham
My wife has used RRT quite successfully to gauge the amount of illegal abalone
fishing in California. Before that, the Fish and Game department did little
more than guess (and of course, underestimate) how much illegal fishing was
going on.

~~~
bugsy
You can't successfully gauge it when you don't know the real numbers to begin
with in order to validate if your method is working.

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zdw
Wouldn't this greatly throw off the results in cases of rare behavior? For
example, if only 1 in 100 (1%) people were leopard killers, but the frequency
of throwing a die is 1 in 6 (16.6_%), how would you prevent the results from
being thrown off by dice-required yes answers?

I'm assuming there's a statistical solution to this - if someone could explain
this or link to one I'd appreciate it.

~~~
hugh3
I'm concerned that some of the respondents wouldn't quite have understood the
rules of the game, and that this might throw the results off significantly.

~~~
Natsu
You could always ask them other questions you already know the answers to in
order to measure that.

~~~
bugsy
That would only, even theoretically, be a possible approach to explore if you
had questions that you knew this group of people were exactly as likely to lie
about as killing protected leopards. How could one know which questions these
would be. They wouldn't. Despite this problem, I would still like to see such
calibration questions added to each round such as "Does astrology work for
you?" and "Have you even been taken by aliens?" The results to these questions
would give some useful data for comparison.

~~~
Natsu
You're assuming they lie. I'm addressing the worry that they might not
understand the rules.

~~~
bugsy
All right. That is a very good question to bring up. Rules like those
described are not as straightforward to understand to ordinary people as they
may seem to the experimenter. I had to read it a couple times to understand
that the idea was to tell the truth if 2-5, and give a fixed response if 1 or
6. Surely there were participants that didn't understand and the number among
rural farmers is going to be different than the number among western college
psychology students upon whom most of these sorts of tests are developed and
calibrated. 6 is an unlucky number, the number of the devil in some cultures.
Other cultures have feelings about 1 (unity), 2 (dualism), 3 (trinity), 4
(chinese good luck, indian sacred number) and 5 (witchcraft). When talking of
small effects, there may be emotions experienced that vary from person to
person depending on their education, IQ, cultural background and environment.
This can skew results in a way that is dependent on the particular population
tested. A person from a culture that believes that 6 is an evil number and a
bad omen may be very slightly more likely to change their response on a 6,
seeing it as a warning. One can't take a test like this that is quite subtle
and looks at tiny effects within noise signals that come not from rocket
engines but from subjective human reactions and dump it on any population and
assume results calibrated on a different population are a valid
interpretation. That would have to be shown first, in cross-cultural
comparison testing.

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ColinWright
I'm disappointed that the title of this submission got changed. I deliberately
chose a title that kept the original flavor, but which tried to show why this
might be relevant to this specific audience.

The title I chose was something like "Getting Feedback - Throwing dice get to
the truth about killing leopards" or something similar. I don't remember
exactly - I'll have to go and look it up.

I understand why the mods don't want titles changed radically, but I spent
significant time and effort getting something that retained the essence of the
original, but which also tied it explicitly to the HN audience without
editorializing or sensationalizing.

Very disappointed.

<http://www.youtube.com/watch?v=84zY33QZO5o>

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tybris
That's pretty smart. It basically anonimizes individual responses, without
harming the statistical outcome.

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gwern
RRT is interesting; reminds me a great deal of the dining cryptographers'
protocol
[https://secure.wikimedia.org/wikipedia/en/wiki/Dining_crypto...](https://secure.wikimedia.org/wikipedia/en/wiki/Dining_cryptographers_problem)

------
Mz
_But won't people soon get wise to the actual intent and clam up again? Not if
the results are used carefully, Jones argues. "It's not going to be used to
criminalise people," she says. Instead, the results could be used to target
conservation outreach efforts and compensation for livestock lost to predators
on areas where ranchers are especially likely to kill carnivores._

This is key. When you criminalize people for trying to meet their own needs,
defend themselves and so on, you create very big problems. It has to be
acceptable to survive, make a living and so on. There has to be a system in
place for resolving conflicts of interest that adequately considers the needs
of both sides.

 _Justice cannot be for one side alone, but must be for both._ \-- Eleanor
Roosevelt

\-------------

Finding the quote I wanted also led to these quotes and I like them:

 _I have always found that mercy bears richer fruits than strict justice._ \--
Abraham Lincoln

 _Justice that love gives is a surrender, justice that law gives is a
punishment._ \-- Mohandas Gandhi

 _We win justice quickest by rendering justice to the other party._ \--
Mohandas Gandhi

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bugsy
The problem, which is obvious to anyone but a researcher with strong bias, is
that 19% of all people have obviously NOT killed a leopard in the last 12
months and therefore this questioning method does not work.

~~~
gwern
Thank you for yet again demonstrating that when a layman says something is
'obvious' and refutes some researchers' work, that layman is really just full
of it.

~~~
bugsy
Your belief this method is scientific, valid, validated cross-culturally and
for different forms of questioning shows that it is you who are the "layman",
assuming by "layman" you mean person ignorant of science, gullible, and
clueless.

