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CLASS #13: EQUILIBRIUM IN THE LABOR MARKET
Labor Market Equilibrium
There is an equilibrium level of real wages w* such that labor demand is equal to labor supply. When w<w* there is excess demand for labor, which induces firms to bid wages up. When w<w* there is excess supply of labor, which induces firms to bid wages down.
Labor Taxes and Equilibrium Wages and Employment
If firms have to pay 10 % of the wage as, say, social security contribution, their perceived cost of labor is 10% higher: the labor demand curve shifts down.

\begin{displaymath}(1-\alpha) A K^{\alpha} N^{-\alpha} = (1+\tau_f)w\end{displaymath}

or

\begin{displaymath}\frac{(1-\alpha) A K^{\alpha} N^{-\alpha} }{1+\tau_f}= w \end{displaymath}

If workers have to pay a 10% tax on their income, their perceived earnings are 10% lower: the labor supply curve shifts up.

\begin{displaymath}U_C(C,L)w(1-\tau_w)=U_L(C,L)\end{displaymath}

or

\begin{displaymath}w=\frac{U_L(C,L)}{U_C(C,L)(1-\tau_w)}\end{displaymath}

Taxes are equivalent to increase the marginal utility of leisure from UL to $\frac{U_L}{1-\tau_w}$, and therefore induce people to work less, for any given pre-tax wage. $\rightarrow$ social security contributions and income taxes lower equilibrium employment.
Unemployment
Measuring unemployment: Labor force= number of employed + number of unemployed Labor force participation rate=Labor force/Adult population (66% in US) In order to be considered unemployed one has to be actively looking for a job. Discouraged workers are not counted as unemployed, but just dropped from the labor force. Frictional unemployment Job search: people looking for the "right" job (example: tenant and landlord). Structural unemployment Low skilled workers: cannot find a job at any wage. Full employment We have full employment when the only kind of unemployment is structural or frictional (no pressure on wages). Natural rate of unemployment= structural + frictional Cyclical unemployment= actual unemployment - natural rate =$u-\bar{u}$
Okun's law
How much does output decrease in % terms when cyclical unemployment increases? Okun's law is an empirical relationship:

\begin{displaymath}\frac{\bar{Y}-Y}{\bar{Y}}=2.5\times (u-\bar{u})\end{displaymath}

when cyclical unemployment rises:
Modeling the natural rate
Why should we be interested in modeling the natural rate? Because it changes over time and, more importantly, it changes a lot across countries.
  Unemployment (%) Long term unemployment
  % % of total unemployment
  74-79 80-89 96 79 89
Germany 3.2 5.9 8.9 19.9 49
France 4.5 9 12.4 30.3 43.9
Spain 5.2 17.5 22.1 27.5 58.5
UK 5 10 8.2 24.5 40.8
US 6.7 7.2 5.4 4.2 5.7
A model of the natural rate
Define U= number of unemployed people;
E= number of employed people;
L= U+E= total labor force; f= job finding rate;
fU= unempl. become empl.; (1-f)U= unempl. stay unempl.;
s= job separation rate; sE= empl. become unempl.
So the law of motion for Unemployment is:

Ut+1=(1-f)Ut+sEt

or

Ut+1=(1-f)Ut+s(L-Ut)

At the steady state (long run) Ut+1= Ut=Us Solve for Us and obtain:

\begin{displaymath}\frac{U_s}{L}=\frac{s}{s+f}\end{displaymath}

As f increases, $\frac{U_s}{L}$ decreases Obtain that the natural rate is a function of the separation rate (s) and of the finding rate (f). What happen when Unemployment Insurance programs are very generous? Incentives to look for a job decrease. But UI programs in Europe were very generous back from the 50's. Why are differences in natural unemployment rates appearing only in the 80's? Sargent and Ljungqvist: human capital story + changes in technology.

 
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Marco Del Negro
2000-02-24