economics of labor, 2013 fall elliott fan lecture 6 slide 1 econ 4009 labor economics i 2013 fall...

Economics of Labor, 2013 FallElliott Fan Lecture 6 slide 1

ECON 4009

Labor Economics I2013 Fall

Elliott FanEconomics, NTU

Lecture 6Human capital

Lecture 6Economics of Labor, 2013 FallElliott Fan


Family background and university quality


Story 1: Destiny at age 6?

• In Project STAR, 11,571 students in Tennessee and their teachers were randomly assigned to classrooms within their schools from kindergarten to third grade.

• One study demonstrates that kindergarten test scores are highly correlated with outcomes such as earnings at age 27, college attendance, home ownership, and retirement savings.


Story 1: Destiny at age 6?They document four sets of experimental impacts:1. Students in small classes are significantly more likely to

attend college and exhibit improvements on other outcomes.

2. Students who had a more experienced teacher in kindergarten have higher earnings.

3. Students who were randomly assigned to higher quality classrooms in grades K-3 – as measured by classmates' end-of-class test scores – have higher earnings, college attendance rates, and other outcomes.

4. The effects of class quality fade out on test scores in later grades but gains in non-cognitive measures persist.


Story 2: Born on the first of September

• Researchers have found that the single start day of schooling every year leads to discrepancy in education outcome.

• In the case of Taiwan, Elliott Fan has found that September 1st born children are 34% more likely to attend university than those born on August 31st.

Lecture 6 slide 9

Introduction• People bring into the labor market a unique set of

abilities and acquired skills known as human capital.

• Workers add to their stock of human capital throughout their lives, especially via job experience and education.

Lecture 6 slide 10

Education: Stylized Facts• Education is strongly correlated with:

o Labor force participation rateso Unemployment rateso Earnings

Lecture 6 slide 11

Present Value Calculations• Present value allows comparison of dollar amounts

spent and received in different time periods. (An idea from finance.)

• Present Value = PV = y/(1+r)t

o r is the per-period discount rate.o y is the future value.o t is the number of time periods.

Lecture 6 slide 12

Potential Earnings Streams Faced by a High School Graduate

A person who quits school after getting her high school diploma can earn A from age 18 until retirement. If she decides to go to college, she foregoes these earnings and incurs a cost of B dollars for 4 years and then earns Stream

B until retirement.

Lecture 6 slide 13

Present value of age-earnings profiles

• The PVs for high school graduates and college graduates are:

2 46

2 3

4 5 46

.......(1 ) (1 ) (1 )

(1 ) (1 ) (1 )

.......(1 ) (1 ) (1 )

HS HS HSHS HS

COL

COL COL COL

w w wPV w

r r r

H H HPV H

r r r

w w w

r r r

Lecture 6 slide 14

The Schooling Model• Real earnings (earnings adjusted for inflation).

• Age-earnings profile: the wage profile over a worker’s lifespan.

• The higher the discount rate, the less likely someone will invest in education (since they are less future oriented).

• The discount rate depends on:o the market rate of interest.o time preferences: how a person feels about giving up today’s

consumption in return for future rewards.

Lecture 6 slide 15

The Wage-Schooling Locus

• The salaries firms are willing to pay workers depend on the level of schooling.

• Properties of the wage-schooling locus.o The wage-schooling locus is upward sloping.o The slope of the wage-schooling locus indicates the increase in

earnings associated with an additional year of education.o The wage-schooling locus is concave, reflecting diminishing returns

to schooling.

Lecture 6 slide 16

The Wage-Schooling Locus

The wage-schooling locus gives the salary that a particular worker would earn if he completed a particular level of schooling. If the worker graduates from high school, he earns $20,000 annually. If he goes to college for 1 year, he earns $23,000. And so on.

0 13 14 1812

30,000

20,000

23,000

25,000

Years of Schooling

Dollars

Lecture 6 slide 17

The Schooling Decision

Years of Schooling

Rate of Discount

s*s

r

r

MRR

The MRR schedule gives the marginal rate of return to schooling, or the percentage increase in earnings resulting from an additional year of school. A worker maximizes the present value of lifetime earnings by going to school until the marginal rate of return to schooling equals the rate of discount. A worker with discount rate r goes to school for s* years.

Lecture 6 slide 18

Schooling and Earnings When Workers

Have Different Rates of Discount

Years of Schooling

Years of Schooling

Rate of Interest

1212 1111

rBO

rAL

MRR

Dollars

wDROP PAL

PBO

wHS

Lecture 6 slide 19

Schooling and Earnings When Workers Have Different Abilities

Years of Schooling

Years of Schooling

Rate of Interest

1211

r

MRRACE

MRRBOB

Dollars

1211

wHS

wACE

PACE

wDROP

Z

Bob

Ace

Ace and Bob have the same discount rate (r) but each worker faces a different wage-schooling locus. Ace drops out of high school and Bob gets a high school diploma. The wage differential between Bob and Ace (wHS - wDROP) arises both because Bob goes to school for one more year and because Bob is more able. As a result, this wage differential does not tells us by how much Ace’s earnings would increase if he were to complete high school (wACE - wDROP).

Lecture 6 slide 20

Education and the Wage Gap• Observed data on earnings and schooling does

not allow us to estimate returns to schooling, because more able persons tend to get more education.

• Ability bias: The extent to which unobserved ability differences exist affects estimates on returns to schooling, since the ability difference may be the true source of the wage differential.

Lecture 6 slide 21

Estimating RRS using a family model

• Y is earnings for individual i of family j• E is years of schooling• X are individual characteristics• Z are family characteristics

0ij ij ij j ijY E X Z

Lecture 6 slide 22

Estimating RRS using a family model

• Assuming that the errors can be decomposed into two components – a family specific term u and an idiosyncratic term v.

• We can apply family fixed-effects model on identical twins

• However, there are limitations on the twin method.

0 ( )ij ij ij j j ijY E X Z u v

Lecture 6 slide 23

Estimating RRS using IVCandidates for IV are• Quarter of birth or month of birth• Policy changes such as the extension of mandatory

education years from 6 to 9 years in Taiwan in 1968.• Discontinuity caused by institutional designs, such as

the cutoff score set by province government in the university education system in China.

Lecture 6 slide 24

Some Evidence

• In studies of twins, presumably holding ability constant, valid estimates of rate of return to schooling can be estimated.o Estimates range from 3% to 15% annual return to a year of education.

• Generally, the rate of return to schooling is higher for workers who were born in states with well-funded education systems.

• RRE is found larger in developing countries than rich countries.

Lecture 6 slide 25

School Quality and the Rate of Return to Schooling

2

3

4

5

6

7

8

15 20 25 30 35 40

Pupil/teacher ratio

Rat

e of

ret

urn

to s

choo

ling

2

3

4

5

6

7

8

0.5 0.75 1 1.25 1.5 1.75 2

Relative teacher wageR

ate

of r

etur

n to

sch

oolin

g

Source: David Card and Alan B. Krueger, “Does School Quality Matter? Returns to Education and the Characteristics of Public Schools in the United States,” Journal of Political Economy 100 (February 1992), Tables 1 and 2. The data in the graphs refer to the rate of return to school and the school quality variables for the cohort of persons born in 1920-1929.

Lecture 6 slide 26

Does class size matter?

• Non-experimental evidence appears to be mixed.

• Using two well-known experiments – STAR in the US and Maimonide’s rule in Israel, researchers have found a negative correlation between class size and education outcomes.

Lecture 6 slide 27

Do Workers Maximize Lifetime Earnings?• The schooling model assumes that workers select their level

of education to maximize the present value of lifetime earnings.

• To test this hypothesis directly, we must observe the age-earnings profile at two points in time.o Unfortunately, once a choice is made, we cannot observe the

earnings associated with the non-choice.

o Thus, using the observed wage differential to determine if the worker selected the “right” earnings stream yields meaningless results.

Lecture 6 slide 28

Schooling as a Signal• Education reveals a level of attainment which

signals a worker’s qualifications or innate ability to potential employers.

• Information that is used to allocate workers in the labor market is called a signal.

• There could be a “separating equilibrium.”o Low-productivity workers choose not to obtain X

years of education, voluntarily signaling their low productivity.

o High-productivity workers choose to get at least X years of schooling and separate themselves from the pack.

Lecture 6 slide 29

Schooling as a Signal

Work types % of work force productivity

High productivity q 200k

Low productivity 1-q 300k

• Suppose there are 2 types of workers:

• In the case of asymmetric information, a pooled equilibrium is reached, and average wage is paid to both types of workers.

Lecture 6 slide 30

Education as a Signal

Workers get paid $200,000 if they get less than y years of college, and $300,000 if they get at least y years. Low-productivity workers find it expensive to invest in college, and will not get y years. High-productivity workers do obtain y years. As a result, the worker’s education signals if he is a low-productivity or a high-productivity worker.

300,000

250,001 y

20,000 y

0

Dollars

Years of Schooling

Costs

Slope = 25,000

300,000

200,000

0

Dollars

Years of Schooling

Costs

Slope = 20,000

(a) Low-Productivity Workers

y y

(b) High-Productivity Workers

200,000

Lecture 6 slide 31

Implications of Schooling as a Signal• For schooling to act as a signal, schooling must

be more “costly” for low-ability workers compared to high-ability workers.

• Social return to schooling (percentage increase in national income) is likely to be positive even if a particular worker’s human capital is not increased.

• Although education may incorporate a signaling aspect, it is well-accepted that education is more than a signal. Education is at least partially an investment in human capital.

Lecture 6 slide 32

On the job training

• Using the PV method in a 2-period model:

2 21 1(1 ) (1 )

w VMPw H VMP

r r

Lecture 6 slide 33

Post-School Human Capital Investments

• Three important properties of age-earnings profiles:o Highly educated workers earn more than less educated

workers.o Earnings rise over time at a decreasing rate.o The age-earnings profiles of different education cohorts

diverge over time (they “fan outward”).o Earnings increase faster for more educated workers.

Lecture 6 slide 34

Age-Earnings Profiles

18 25 32 39 46 53 60200

500

800

1100

1400

1700

2000

2300

2600

Men

Age

We

ek

ly E

arn

ing

s

Some college

College Graduates

High school graduates

High school dropouts

Lecture 6 slide 35

Age-Earnings Profiles

18 25 32 39 46 53 60100

300

500

700

900

1100

1300

1500

Women

Age

We

ek

ly E

arn

ing

s

Some college

High school graduates

College Graduates

High school dropouts

Lecture 6 slide 36

On-The-Job Training• Most workers augment their human capital

stock through on-the-job training (OJT) after completing education investments.

• Two types of OJT:o General: training that is useful at all firms once it is acquired.o Specific: training that is useful only at the firm where it is acquired.

Lecture 6 slide 37

Implications• Firms only provide general training if they do

not pay the costs.

• In order for the firm to willingly pay some of the costs of specific training, the firm must share in the returns to specific training. Engaging in specific training eliminates the possibility of the worker separating from the job in the post-training period.

Lecture 6 slide 38

The Acquisition of Human Capital Over the Life Cycle

MC

MR20

MR30

Dollars

0 Q30 Q20

Efficiency Units

The marginal revenue of an efficiency unit of human capital declines as the worker ages (so that MR20, the marginal revenue of a unit acquired at age 20, lies above MR30). At each age, the worker equates the marginal revenue with the marginal cost, so that more units are acquired when the worker is younger.

Lecture 6 slide 39

Age-Earnings Profiles and OJT• Human capital investments are more profitable the

earlier they are taken.

• The Mincer earnings function:o Log(w) = a·s + b·t – c·t2 + other

variables.o The “overtaking age” is t* and indicates

the time when the worker slows down acquisition of human capital to collect the return on prior investments so as to “overtake” earnings of those that did not undertake similar investments.

Lecture 6 slide 40

The Age-Earnings Profile Implied by Human Capital Theory

Dollars

Age-Earnings Profile

Age

The age-earnings profile is upward-sloping and concave. Older workers earn more because they invest less in human capital and because they are collecting the returns from earlier investments. The rate of growth of earnings slows down over time because workers accumulate less human capital as they get older.

Lecture 6 slide 41

Policy Application: Evaluating Government Training Programs

• Aimed at exposing disadvantaged and low-income workers to training programs.

• $4 billion of federal spending per year.

• Studies of the return to these human capital investments are unclear, largely because of self-selection bias.

Lecture 6 slide 42

Social Experiments

• National Supported Worker Demonstration (NSW).o Results of the NSW suggest a 10% return to

investments in human capital for workers treated under the program.

economics of labor, 2013 fall elliott fan lecture 6 slide 1 econ 4009 labor economics i 2013 fall...

Documents