Corrida de lémures

Quem quer escapar ao precipício? 

Família de lémures. Foto © AFP

Recebi um elucidativo artigo sobre a matemática da crise actualmente em curso, que junto na íntegra ao meu comentário.

Concluo da sua leitura o seguinte:

1. Tornar a Europa competitiva significa, de acordo com Thambapillai, deflação e desemprego estrutural — certo?
2. Mas o problema é que se todos entrarem neste corrida de lémures para o abismo —depois do Japão, a China, os EUA, e agora a Europa— o que é que sobra?
3. Talvez alguém se lembre, antes de esta década chegar ao fim, e entre os mais atingidos por este suicídio em massa —os países mais pobres, populosos e jovens do planeta— de responder com uma guerra, simultaneamente assimétrica e simétrica!
4. Será isto que os piratas anglo-americanos andam a preparar? Quem lhes garante que se sairão oura vez impunes de mais um morticínio à escala global?
5. É melhor começar a chamar os burros pelos nomes!

What is meant (in monetary policy) by the ‘zero lower bound problem’?
 By Ravin Thambapillai

tldr;
The zero lower bound problem is when the Central Bank wants to set the interest rate to be negative, but can't, because otherwise people would withdraw all their money from banks and just hold cash. Because the central bank can't choose its preferred interest rate, you get unemployment and disinflation, or worse, deflation.

The Zero Lower Bound problem is the problem that if the equilibrium interest rate falls below 0, the economy can fall into a self perpetuating slump, which can take an unusually long time to get out of.

Firstly:
1. The interest rate cannot go below 0 because if it did, those holding bank deposits might simply withdraw their deposits and hold the money as cash (which earns 0 nominal return, as opposed to a negative nominal return, which bank deposits would be earning).

Secondly:
2. The interest rate equilibriates inflation and unemployment. That is, if inflation is too high, raising the interest rate will bring it down. If unemployment is too high, lowering the interest rate will bring that down.

The Central Bank sets the interest rate according to a very complicated version of an equation that is effectively this (called the Taylor Rule):



i is the interest rate,
pi is the inflation rate
r is the real interest rate, or i - pi
a is just some coefficient that reflects how much you dislike excess inflation and excess unemployment (it can be any number but should be above 0, since excess is by definition too much)
the * represents "what this variable would be in the ideal economy
y is output/employment
y bar is output/employment in the ideal economy (you can have too much output, if that output starts causing unwanted inflation).
the t is basically irrelevant, but means "at time t"

(This equation says the interest rate should be set to the interest rate at equilibrium, plus some amont to adjust for unwanted inflation, minus some amount to adjust for unwanted unemployment).

Now
Imagine you have the following scenario:
Unemployment is high, so
is negative

inflation is below the target amount or equal to it (central banks tend to target about 2% inflation) so

is also negative or 0.
We can therefore conclude, that the optimal interest rate must satisfy:
now, by definition:

So:

But assuming

then you get that

 

But, we've already said this is impossible (its point 1 in this exposition), so in other words, the central bank cannot set an interest rate low enough to achieve equilibrium in the economy.

The consequence of this is that the interest rate must get set at best at 0, which is too high, and prevents the economy from achieving equilibrium employment. The economy therefore cannot achieve/restore full employment. Instead grinding disinflation or worse deflation and low employment continues, until eventually the country's prices have fallen so far that its exports look very cheap and it finds international markets for its goods.

in Quora 

Actualização: 26 jan 2012 14:16