
Cobra effect - shawndumas
https://secure.wikimedia.org/wikipedia/en/wiki/Cobra_effect
======
ChuckMcM
Nice link.

TL;DR version - Cobras are a problem, pay a bounty for dead cobras, people
start farming cobras to get the bounty. Kill of the bounty and at the end of
the exercise you have more cobras than before.

If you do systems analysis, you see this as optimizing the wrong variable.
What they wanted were "fewer cobras" but they expressed by asking for "cobra
corpses."

The conundrum is identical to the logical fallacy of attempting to prove a
negative statement. You can't articulate or measure a 'cobra void' so its hard
to reward for it or incentivize it.

In such systems you can either adapt the system to be unaffected by the
undesirable trait (hard to do with cobras, there is only so much anti-venom to
go around) Or to establish negative incentives around the presence of cobras
(say fining people where a cobra is found on their property).

The goal of course is understanding what is the desired state of the system
and targeting an input that only amplifies that state and not some other
state.

~~~
vecter
What do you mean by "the logical fallacy of attempting to prove a negative
statement?". I can prove the negative statement "I did not assassinate JFK" by
citing the fact that I wasn't born yet.

You're right in that in this particular case, the practical difficulties of
quantifying "less cobra-ness" or "cobra void" as you call it is difficult, but
there are plenty of cases where quantifying the absence of something is
straightforward.

~~~
rosser
Strictly speaking, you're proving the positive assertion that you were born
after the assassination, which is incompatible with your having been the
assassin. You can only prove or disprove a positive assertion. "Proving a
negative" is done by proving a positive assertion that's contrary to, or
incompatible with the thing you're trying to "disprove".

~~~
vecter
If proving the positive assertion implies the negative assertion, what's the
difference?

~~~
anigbrowl
I do not believe in the existence of fire-breathing dragons outside of
fiction, but I can't _prove_ they don't exist. See also: UFOs, angels, god(s),
and so on. In logic, the onus is on the person making the positive claim (that
such things do exist) to furnish the evidence to back it up. The skeptic's
lack of knowledge is not proof of non-existence, of course.

~~~
vecter
I'm talking about mathematical truths for which establishing non-existence
follows directly from proving a positive assertion, not that white ravens
don't exist.

~~~
anigbrowl
I understand that, but 'proving a negative' is philosophical shorthand for the
latter rather than the former. You are just going to have to put up with the
slight vagueness of the term.

------
joejohnson
This reminds me of that Simpson's episode "Bart the Mother". The town gets
overrun with Bolivian tree lizards:

Skinner: Well, I was wrong; the lizards are a godsend.

Lisa: But isn't that a bit short-sighted? What happens when we're overrun by
lizards?

Skinner: No problem. We simply release wave after wave of Chinese needle
snakes. They'll wipe out the lizards.

Lisa: But aren't the snakes even worse?

Skinner: Yes, but we're prepared for that. We've lined up a fabulous type of
gorilla that thrives on snake meat.

Lisa: But then we're stuck with gorillas!

Skinner: No, that's the beautiful part. When wintertime rolls around, the
gorillas simply freeze to death.

~~~
canistr
But lizards are cold-blooded. Wouldn't they just freeze to death in the winter
as well?

~~~
hvs
Not as humorously.

------
protomyth
In Admiral Gallery's book "Clear the Decks!", he describes how as commander of
the Fleet Air Base in Reykjavík, Iceland he put a 0.25 bounty per rat caught.
He noticed an immediate decline in rats, but noticed that he was still paying
out about the same amount of money in bounties. He later discovered that his
personnel were paying people at the British and US Air Force bases a dime per
rat and smuggling them into the Navy base. He decided not to crack down on it
since he was cleaning up the other bases.

------
jswanson
When the British first started sending criminals to Australia, only 40%
survived the journey. Measures such as 'increased standards' or paying more
did nothing to increase this statistic.

Eventually the decided to pay per prisoner delivered alive and well, instead
of paying in advance. Survival rate increased to over 98%

[http://www.thefreemanonline.org/columns/the-power-of-
incenti...](http://www.thefreemanonline.org/columns/the-power-of-incentives/)

~~~
kalleboo
That anecdote doesn't pass the smell test. The article says "the 1860's".
Quoth wikipedia: «The last convict ship to be sent from England, the St.
Vincent, arrived in 1853». Another source[1] states that the worst death rate
of the fleet was 33%, far below the 60% in your source.

Makes for a great story/example though! Which I guess is how these anecdotes
propagate.

[1] <http://www.historyaustralia.org.au/ifhaa/ships/2ndfleet.htm>

~~~
benjoffe
I read the same story in The Fatal Shore [1] which to my knowledge is a very
well researched/factual book on early convict history (though I don't recall
the success rate being initially as low as 40%, it was low though).

[1] [http://www.amazon.com/Fatal-Shore-Epic-Australias-
Founding/d...](http://www.amazon.com/Fatal-Shore-Epic-Australias-
Founding/dp/0394753666)

------
DanielStraight
Two thoughts:

1\. They should've reduced the reward over time. If the effort had been
successful, there would've been fewer snakes, and less need to get the snake
population under control. This makes economic sense event without considering
this effect. If there's a million snakes, you really need someone to do
something about it. If there's only 10k, who cares?

2\. This is why it's important to focus on the actual goal. The goal was not
to kill snakes. The goal was to have fewer snakes. Killing snakes was just a
means to an end. Actually, the goal wasn't even fewer snakes, it was to reduce
the risk of dying from a snake bite. A successful anti-venom would've been
just as much a solution as the eradication of the snakes. Of course it's a lot
harder to measure, "Are you doing something which is likely to reduce the risk
of me dying from a snake bite?" than "Did you kill a snake?"

~~~
CapitalistCartr
Breeding another, non-poisonous variety of snake to compete in the same
environmental niche with the cobras would have likely been more effective.
That's what my family does in Virginia to combat the rattlesnakes.

~~~
bh42222
How would a non-poisonous snake compete? It will have fewer predator defenses,
and hunting for its prey will be very different, possibly harder. Wouldn't the
poisonous snake out-compete it, unless it ends up in a different niche?

~~~
Someone
TANSTAAFL. Being poisonous takes effort. You need to have defenses against
your own poison, spend energy producing often complex molecules, etc.

Not spending energy on being poisonous means that a snake can spend it
elsewhere; run a bit harder, lay more eggs, lay eggs earlier, whatever.

------
moss
The building I work in once had a contest: whichever floor recycled the most
paper in a month got an ice cream party.

------
ianferrel
This is a nice story, but I'm not sure it really adds up.

If you're breeding poisonous snakes to turn in for a reward, and the reward
goes away, are you really going to release live poisonous snakes, or are you
just going to kill the ones you have and not breed more?

~~~
matwood
I'm sure many people mean to kill them or they keep them for awhile as pets
and then at some point they escape. Look at FL with all the boa
constrictor/python problems they have.

~~~
ianferrel
That might be the explanation.

Are there really enough people who keep poisonous snakes as pets for this to
happen? I don't think the Florida situation is analogous because of how much
less dangerous constrictors are than cobras.

------
rdl
This wikipedia article got quoted during discussions of how much to pay
civilian casualties (caused by coalition/US forces and contractors) in Iraq
and Afghanistan -- specifically, they didn't want to set compensation high
enough to encourage people to intentionally get killed to provide for their
families, because they definitely would. :(

------
VMG
Reminds me of the story of archaeologists paying for bones. Which curiously
became smaller and smaller with time.

------
jroid
Sounds to be the same as "The law of unintended consequences"
<http://en.wikipedia.org/wiki/Unintended_consequences>

~~~
xentronium
Or, even more precisely, perverse incentives.

<http://en.wikipedia.org/wiki/Perverse_incentive>

~~~
drats
At its most sinister.

[http://en.wikipedia.org/wiki/Congo_Free_State#Humanitarian_d...](http://en.wikipedia.org/wiki/Congo_Free_State#Humanitarian_disaster)

------
MrVitaliy
Does anyone else see a possible corollary with Anti-Virus industry and virus
writers?

~~~
lsc
I dono. I have a family member (a database interface programmer) who insisted
that virus writers are somehow being paid by the anti-virus companies, back in
the boot sector virus days. I mean, his logic said, who would go through all
that effort for free, and who benefits?

~~~
yters
True, and if your AV company also wrote all the viruses, your product would be
the best at blocking them.

------
mhb
And incentives for ethanol use lead to rainforest destruction:

[http://www.time.com/time/magazine/article/0,9171,1725975,00....](http://www.time.com/time/magazine/article/0,9171,1725975,00.html)

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OnesimusUnbound
The plan back fired because the people optimized for the reward, instead of
the long term goal of reducing the number of deaths, like the development of
anti-venom mentioned previously.

I read the article about Lean Software Development and one of the concept the
stuck me is banning local optimization (<http://drdobbs.com/184414744>).

------
wanderful
See also, the iatrogenic effect, where the effects of the solution are worse
than the problem.

<http://en.wikipedia.org/wiki/Iatrogenesis>

------
AbyCodes
_The term 'Cobra effect' stems from an anecdote set at the time of British
rule of colonial India. The British government was concerned about the number
of venomous cobra snakes. The Government therefore offered a reward for every
dead snake. Initially this was a successful strategy as large numbers of
snakes were killed for the reward. Eventually however the Indians began to
breed cobras for the income.

When this was realized the reward was canceled, but the cobra breeders set the
snakes free and the wild cobras consequently multiplied. The apparent solution
for the problem made the situation even worse.

A similar incident occurred in Hanoi, under French colonial rule, where a
program paying people a bounty for each rat pelt handed in was intended to
exterminate rats. Instead, it led to the farming of rats._

If the intention was to decrease the incidents of Cobras/rats causing problems
to humans, then isn't Cobra effect a success?

~~~
stonemetal
Short term success, medium term worsening of the problem, long term no change.

------
dhruvbird
Your company wants you to work more, so it has this "you must be in office for
X hrs every day" and then they realize that people are spending 0.3x of their
time in the canteen, so they decide to exclude canteen time, so the employees
start playing games at their terminals. They decide to ban games - employees
turn to facebook. Ban facebook, everyone becomes unproductive and grumpy. The
company decides that this hrs. policy isn't working well, so decides to get
rid of it. The joy stricken emloyees run wild and no work happens.

------
Lost_BiomedE
My favorite version is during the decline of communist Russia. One example was
quotas on furniture factories enforced by the pound, resulted in 2000lb sofas.
Another was number of military boots made, resulting in all the leather and
soles made but not assembled into an actual boot.

------
dennisgorelik
They could have taxed "Cobra farmers" and introduce a nice reward for people
pointing out to such farmers.

~~~
khafra
That's the Vetinari Solution:
[http://lesswrong.com/lw/2ev/rationality_quotes_july_2010/29b...](http://lesswrong.com/lw/2ev/rationality_quotes_july_2010/29bv)

------
jinushaun
The power of human ingenuity. If there's money to be made, someone will try to
make money off of it.

------
astrofinch
"When this was realized the reward was canceled, but the cobra breeders set
the snakes free and the wild cobras consequently multiplied."

What if they had announced that rewards would stop being offered in a month?
That would give cobra farmers a chance to cash out on their supply.

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kamakazizuru
From an economics perspective, there would have been a simple way to solve the
problem. Create an imaginary market for cobra corpses. Basically the British
government could have simply paid a price = 1 Rupee (or whatever max price
they were willing to apy) /(total number of cobras purchased in the last
Period of time) {where the period of time would obviously need to be adjusted
for it to be sensible so that farmers dont just hold onto snakes and then come
with many at once).

The denominator could also be adjusted based on some biological factors - i.e.
how long does it take to breed a cobra, what is the estimated number of cobras
out there, so on and so forth.

Further more there could be limits to the number of cobra that any one seller
can sell in a the aformentioned period. As well as limit to the total number
of cobras purchased in each period - (i.e. - we've bought out enough for now -
thanks).

I could go on...

~~~
RockyMcNuts
LOL but I think you're proving the point Hayek quoted above.

In programming there's always another bug, in economics there's always another
unintended consequence or negative externality.

------
bbq
See also: patents

------
adolph
Was anyone else looking forward to an article about always being to bail out
when GI Joe's laser hit your plane/helicopter/whatever?

