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Labor Economics. Stepan Jurajda Office #2 (2 nd floor) CERGE-EI building (Politickych veznu 7) [email protected] Office Hour: Tuesdays after class. Introduction. Consider the distribution of wages: What can explain why some people earn more than others?

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Labor economics

Labor Economics

Stepan Jurajda

Office #2 (2nd floor) CERGE-EI building

(Politickych veznu 7)

[email protected]

Office Hour: Tuesdays after class


Introduction
Introduction

  • Consider the distribution of wages:

    What can explain why some people earn more than others?

    (based on exposition by Alan Manning)



Models of distribution of wages
Models of Distribution of Wages (£1 to £100 per hour)

  • Start with perfectly competitive model

  • Assumes labour market is frictionless so a single market wage for a given type of labour – the ‘law of one wage’ (note: this assumes no non-pecuniary aspects to work so no compensating differentials)

  • ‘law of one wage’ sustained by arbitrage – if a worker earns CZK100 per hour and an identical worker for a second firm earns CZK90 per hour, the first employer could offer the second worker CZK95 making both of them better-off


The employer decision the demand for labour
The Employer Decision (£1 to £100 per hour)(the Demand for Labour)

  • Given exogenous market wage, W, employers choose employment, N to maximize:

  • Where F(N,Z) is revenue function and Z are other factors affecting revenue (possibly including other sorts of labour)



The worker decision the supply of labour
The Worker Decision (£1 to £100 per hour)(the Supply of Labour)

  • Assume the only decision is whether to work or not (the extensive margin) – no decision about hours of work (the intensive margin)

  • Assume a fraction n(W,X) of individuals want to work given market wage W; there are L workers. X is other factors influencing labour supply.

  • The labour supply curve will be given by:


Equilibrium
Equilibrium (£1 to £100 per hour)

  • Equilibrium is at wage where demand equals supply. This also determines employment.

  • What influences equilibrium wages/employment in this model:

    • Demand factors, Z

    • Supply Factors, X

  • How these affect wages and employment depends on elasticity of demand and supply curves


What determines wages
What determines wages? (£1 to £100 per hour)

  • Exogenous variables are demand factors, Z, and supply factors, X.

  • Statements like ‘wages are determined by marginal products’ are a bit loose

  • True that W=MRPL but MRPL is potentially endogenous as depends on level of employment

  • Can use a model to explain both absolute level of wages and relative wages. Go through a simple example:


A simple two skill model
A Simple Two-Skill Model (£1 to £100 per hour)

  • Two types of labour, denoted 0 and 1. Assume revenue function is given by:

  • You should recognise this as a CES production function with CRS



  • As W=MPL we must have: (£1 to £100 per hour)

  • Write this in logs:

  • Where σ=1/(1-ρ) is the elasticity of substitution

  • This gives relationship between relative wages and relative employment


A simple model of relative supply
A Simple Model of Relative Supply (£1 to £100 per hour)

  • We will use the following form:

  • Where ε is elasticity of supply curve. This might be larger in long- than short-run

  • Combining demand and supply curves we have that:

  • Which shows role of demand and supply factors and elasticities.


Data from the us
Data from the US (£1 to £100 per hour)


What about unemployment
What about unemployment? (£1 to £100 per hour)

  • As defined in labor market statistics (those who want a job but have not got one) does not exist in the frictionless model.

  • Anyone who wants a job at the market wage can get one (so observed unemployment must be voluntary).

  • Failure of this model to have a sensible concept of unemployment is one reason to prefer models with frictions.


Before we go there a reminder
Before we go there, a reminder (£1 to £100 per hour)

  • Unemployment has different definitions (ILO, registered)

  • US-EU unemployment gap used to be different

  • An unemployment rate does not mean much without an employment rate


The distribution of wages in imperfect labour markets
The Distribution of Wages in Imperfect Labour Markets (£1 to £100 per hour)

  • Discuss a simple variant of a model of labour market with frictions – the Burdett-Mortensen 1998 IER model. Here, MPL=p with perfect competition but with frictions other factors are important.

  • Frictions are important: people are happy (sad) when they get (lose) a job. This would not be the case in the competitive model.


Labour markets with frictions cont
Labour Markets with frictions, cont. (£1 to £100 per hour)

  • Assume that employers set wages before meeting workers (Pissarides assumes that there is bargaining after they meet. Hall & Krueger: 1/3 wage posting 1/3 bargained.)

  • L identical workers, get w (if work) or b.

  • M identical CRS firms, profits= (p-w)n(w). There is a firm distribution of wages F(w).

  • Matching: job offers drawn at random arrive to both unemployed and employed at rate λ; exog. job destruction rate is δ.


Labour markets with frictions cont1
Labour Markets with frictions, cont. (£1 to £100 per hour)

  • Unemployed use a reservation wage strategy to decide whether to accept the job offer or wait for a better one (r=b).

  • 1. steady state unempl.: Inflow = Outflow: δ(1-u) = λ[1-F(r)]u + 2. In equilibrium F(r)=0 (why offer a wage below r? – you’ll make 0 profits) => equilibrium u= δ / (δ+λ).

  • Employed workers quit: q(w)= λ[1-F(w)]


Labour markets with frictions cont2
Labour Markets with frictions, cont. (£1 to £100 per hour)

  • In steady state, a firm recruits and loses the same number of workers: [δ+q(w)]n(w)=R(w)= λL/M[u+(1-u)N(w)] where N(w) is the fraction of employed workers who are paid w or less.

  • Derive n(w): firm employment and profit. Next, get equilibrium wage distribution F(w) & average wage E(w).

  • EQ: all wages offered give the same profit (π=(p-w)n(w) higher w means higher n(w).) + no other w gives higher profit.


  • Average wage is given by: (£1 to £100 per hour)

  • So the important factors are

    • Productivity, p

    • Reservation wage, b

    • Rate of job-finding, λ and rate of job-loss, δ

    • i.e. a richer menu of possible explanations

  • But, also equilibrium wage dispersion (even when workers are all identical; a failure of the ‘law of one wage’) so luck also important.

  • Perfect competition if λ/δ=∞. Frictions disappear. Competition for workers drives w to p (MP).


Institutions also important
Institutions also important (£1 to £100 per hour)

  • Even in a perfectly competitive labour market institutions affect wages/emplmnt

  • Possible factors are:

    • Trade unions

    • Minimum wages

    • Welfare state (affects incentives, inequality) Example: higher unempl. benefit increases the wage share and reduces inequality, but it also increases the unempl. rate thus making the distribution of income more unequal.


Stylized facts about the distribution of wages
Stylized Facts About the Distribution of Wages (£1 to £100 per hour)

  • There is a lot of dispersion in the distribution of ‘wages’

  • Most commonly used measure of wages is hourly wage excluding payroll taxes and income taxes/social security contributions

  • This is neither reward to an hour of work for worker nor costs of an hour of work to an employer so not clear it has economic meaning

  • But it is the way wage information in US CPS, EU LFS is collected.




Overall distribution of cz hourly wages 1q2006 median 105czk 5 th percentile 55czk 95 th 253
Overall Distribution of CZ Hourly Wages (£1 to £100 per hour)1Q2006: median: 105CZK, 5th percentile: 55CZK, 95th: 253


Comments
Comments (£1 to £100 per hour)

  • Sizeable dispersion (there is also much dispersion in firm-level productivity)

  • Distribution of log hourly wages reasonably well-approximated by a normal distribution (the blue line)

  • Can reject normality with large samples

  • More interested in how earnings are influenced by characteristics


The earnings function
The Earnings Function (£1 to £100 per hour)

  • Main tool for looking at wage inequality is the earnings function (first used by Mincer) – a regression of log hourly wages on some characteristics:

  • Earnings functions contain information about both absolute and relative wages but we will focus on latter


Interpreting earnings functions
Interpreting Earnings Functions (£1 to £100 per hour)

  • Literature often unclear about what an earnings function meant to be:

    • A reduced-form?

    • A labour demand curve (W=MRPL)?

    • A labour supply curve?

  • Much of the time it is not obvious – perhaps best to think of it as an estimate of the expectation of log wages conditional on x


An example of an earnings function uk lfs
An example of an earnings function – UK LFS (£1 to £100 per hour)

  • This earnings function includes the following variables:

    • Gender

    • Race

    • Education

    • Family characteristics (married, kids)

    • (potential) experience (=age –age left FT education)

    • Job tenure

    • employer characteristics (union, public sector, employer size)

    • Industry

    • Region

    • Occupation (column 1 only)



Education variables
Education variables (£1 to £100 per hour)


Family characteristics
Family Characteristics (£1 to £100 per hour)


Experience job tenure
Experience/Job Tenure (£1 to £100 per hour)


Employer characteristics
Employer Characteristics (£1 to £100 per hour)




Occupation relative to craft workers only 1 st column
Occupation (relative to craft workers) – only 1 (£1 to £100 per hour)st column


Stylized facts to be deduced from this earnings function
Stylized facts to be deduced from this earnings function (£1 to £100 per hour)

  • women earn less than men

  • ethnic minorities earn less than whites

  • education is associated with higher earnings

  • wages are a concave function of experience, first increasing and then decreasing slightly

  • wages are a concave function of job tenure

  • wages are related to ‘family’ characteristics

  • wages are related to employer characteristics e.g. industry, size

  • union workers tend to earn more (?)


The same stylized facts for cz
The same stylized facts for CZ (£1 to £100 per hour)


The variables included here are common but can find many others sometimes included
The variables included here are common but can find many others sometimes included

  • Labour market conditions – e.g. unemployment rate, ‘cohort’ size

  • Other employer characteristics e.g. profitability

  • Computer use- e.g. Krueger, QJE 1993

  • Pencil use – e.g. diNardo and Pischke, QJE 97

  • Beauty – Hamermesh and Biddle, AER 94

  • Height – Persico, Postlewaite, Silverman, JPE 04

  • Sexual orientation – Arabshebaini et al, Economica 05


Raises question of what should be included in an earnings function
Raises question of what should be included in an earnings function

  • Depends on question you want to answer

  • E.g. what is effect of education on earnings – should occupation be included or excluded?

  • Note that return to education lower if include occupation

  • Tells us part of return of education is access to better occupations – so perhaps should exclude occupation

  • But tells us about way in which education affects earnings – there is a return within occupations


Other things to remember
Other things to remember function

  • May be interactions between variables e.g. look at separate earnings functions for men and women. Return to experience lower for women but returns to education very similar.

  • R2 is not very high – rarely above 0.5 and often about 0.3. So, there is a lot of unexplained wage variation: unobserved characteristics, ‘true’ wage dispersion, measurement error.


Problems with interpreting earnings functions
Problems with Interpreting Earnings Functions function

  • Earnings functions are regressions so potentially have all usual problems:

    • endogeneity e.g. correlation between job tenure and wages

    • omitted variable e.g. ‘ability’

    • selection – not everyone works e.g. the earnings of women with very young children

  • Tell us about correlation but we are interested in causal effects and ‘correlation is not causation’


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