Discussion Papers In Economics
And Business

The effects of education externality on schooling
Koichi Fukumura
Discussion Paper 15-05

Graduate School of Economics andOsaka School of International Public Policy (OSIPP)
Osaka University, Toyonaka, Osaka 560-0043, JAPANThe effects of education externality on schooling
Koichi Fukumura
Discussion Paper 15-05

April 2015

Graduate School of Economics andOsaka School of International Public Policy (OSIPP)
Osaka University, Toyonaka, Osaka 560-0043, JAPANThe effects of education externality on schooling∗
Koichi Fukumura†

Abstract
This study theoretically investigates the effects of educational envy on schooling decisions. I develop a model
where in workers enjoy utility from their levels of education and consumption. Moreover, worker’s utility also
depends on other worker’s education levels, i.e., we assume the “keeping up with Joneses” effect in education.
The main result of this study is that such envy causes workers to make decisions on education level that differ fromthe decision made when envy is not considered. This result can explain the United States-Japan differences in
the relationship between wages and schooling decisions. Analysis from a social planner’s perspective reveals thatcertain conditions on parameters can change the social preferences for the education level selected by individuals.
Moreover, the model indicates that the economy may be overeducated in terms of the education for education’s
sake situation.

JEL Classification: I26; I21; I31; E24
Keywords: Education; Externality; Social preference; Multiple equilibria∗ I am very thankful to my supervisor Yasuhiro Sato for his extraordinary supports for my study. I am deeply indebted to Tetsuo Ono and
Masaru Sasaki for their comments on this study. And I have greatly benefited from the discussion with Yuki Otsu. The author is responsible
for the all remaining errors.
† Graduate School of Economics, Osaka University, 1-7 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. E-mail: u958467k@ecs.osakau.ac.jp.

1 Introduction
Education is frequently viewed as playing a very important role in human society. For developing countries, theUnited Nations established the eight Millennium Development Goals (MDGs). The second target of the MDGs
is to achieve a full course of primary schooling for all children throughout the world by 2015. As a result, mostdeveloping countries have attempted to facilitate elementary education. For developed countries, primary education
is provided to almost of all children, and the schooling rates of more higher education have increased. Therefore,
these countries have developed more sophisticated societies. Furthermore, higher education has contributed to both
the growth of specific countries and overall global growth through technical innovations.
In the economic literature, Becker (1962) is famous for developing the theory of human capital formation.
His study investigated the effect of human capital, which is accumulated through education and training, andaffects the economy by considering the marginal benefits and marginal costs of education. Subsequently, manystudies have been conducted on the relationship between human capital investment and its returns. The returns areprimarily measured using wages or several other monetary measures. Therefore wages are frequently viewed as
being determined by education or human capital. Mincer (1958) theorized the wage equation into the Mincerian
wage equation, which is frequently used to determine the factors that affect wages. Moretti (2004) used Mincerian
wage equation to empirically study the relationship among schooling year, place of habitat, and wages. The study
showed that increasing the number of highly educated people in a Metropolitan Statistical Area (MSA) induces anincrease in the wages in that MSA, called the spillover effect. And Calvó-Armengol et al. (2009) showed that theschool performance of children in the United States is significantly and positively affected by social networks after
controlling for other factors. This result suggests a positive education externality, as this study assumes. Thoughempirical studies are fewer in Japan because of data restrictions, Hashimoto and Heath (1995) estimated the income
elasticities of educational expenditures in Japan. The average estimated elasticity of education is 1.72, a result thatsuggests the existence of an education externality in Japan. And there are many other empirical researches which
supports the externalities. Therefore, the existence of human capital externality is undoubted.
We review actual data on education and wages to determine the relationship between wage differences andschooling decisions. Standard economic theory states that the growth of wage differences between educations
induces an increasing in schooling length. However, there exist some data that are contrary to the theory. Wage
differences between high school graduates and university graduates are typically introduced; however, this study
introduces wage differences of high school graduates and non-high school graduates between the United States andJapan. Figure 1 depicts data from the Current Population Survey (CPS) Historical Time Series Tables on School
Enrollment in the United States and time series data from School Basic Survey in Japan. In the United States, therate of high school graduation increased slightly since 1970. In contrast, in Japan, the rate of high school enrollment
significantly increased between 1950 and 1980, and increased slowly after 1980. Standard economic theory statesthat the growth in high school graduation rates induces a reduction in relative wages between those who graduate
and those who do not. Figure 2 from the CPS data indicates that wages in the United States declined relative to the
1

1
.9
.8
.7
.6
.5
1950

1960

1970

1980
year

Enrollment Rate in Japan

1990

2000

2010

Graduation Rate in U.S.

The US. rate represents the rate of high school graduates in the age group of 18-24 years old from the CPS survey. The Japanese rate shows
the rate of high school enrollments in the population who completed 9 years education from the School Basic Survey. I can not obtain thegraduation rate in Japan, however, the high school quitting rate in Japan is in the range of approximately 2-3% , I obtained this from the data.

Figure 1: U.S. high school graduation rates and enrollment rates in Japanwages of high school graduates—as predicted by economic theory. In contrast, Japanese relative wages indicate
two unreasonable movements and values. First, despite the growing number of high school students, wages ofjunior high school graduates did not decline. Typically, the labor force flows into high relative wage sectors ifother conditions remain constant. However, the data show flatter movements. Second, the most unusual pointis that the wage levels of high school graduates and non-graduates are almost identical, which is obvious from
Figure 2. Figure 2 depicts that the relative wage of high school non-graduates is approximately 1, suggesting that
graduating from high school does not affect the wages in Japan. Therefore, schooling decision of the Japaneseis viewed as also being determined by non-monetary factors.1 These puzzling motions and values are naturally
caused by the “keeping up with the Joneses” thoughts of individuals getting an education. That is, a person decides
to go to school not because wages of high school graduates are high but because others are attending school. In
Japan, many parents want to send their children to highly ranked high schools and universities regardless of thecost. For example, they typically pay more than ¥1 million (approximately more than US$8,500) per year tocram schools (Jyuku in Japanese), in addition to paying the high school tuition to enroll in such highly ranked
educational institutions. Moreover, the high cost of education cost is seen as a contributing factor to the low birthrate in Japan.
Before we begin to describe the model, we review the “keeping up with Joneses” consumption effects as the educational effect is similar. Many researchers studied the “keeping up with Joneses” consumption effects. The firststudy that we address is Abel (1990), who developed an asset pricing model that considered aggregate consumption per capita, investigated its effect on asset pricing, and showed that the “keeping up with the Joneses” effect is
1 In Japan, when we consider bonuses in wages, the ratio of wages with bonus was 1.16, whereas the ratio of wages without bonus was 1.11

in 2013. Bonuses seem to increase the wage difference. However, the increase is not as large when we compared with the increase in the ratioof wages in Japan between high school graduates and university graduates, 1.33 to 1.41. Therefore, the wage difference between high school
graduates and non-graduates in Japan is not as wide even we considered bonuses.

2

1.6
1.4
1.2
1
1950

1960

1970

1980
year

Relative Wage in Japan

1990

2000

2010

Relative Wage in U.S.

The data of U.S. relative wage is median data from weekly and hourly earnings data from the CPS. The data of Japan’s relative wage is meandata from Basic Survey on Wage Structure. The difference between median and mean is due to data availability. The U.S. data is the ratio of
median relative wages of males, over 25 year old that are high school graduates to those that not high school graduates. The Japanese data is
the ratio of average relative wages of working males that are high school graduates to those that are not high school graduates.

Figure 2: Relative wages of high school graduates and non-graduates in the U.S. and Japana source of equity premiums. Similarly, Abel (1990) indicated that the “keeping up with Joneses effect” may be
a source of the puzzle we mentioned in Figure 1 and 2. Ljungqvist and Uhlig (2000) explored taxation effects on“keeping up with the Joneses” consumption. Their study found that although several externalities exist, government taxation is a good way to control the economy. The implication of their paper is utilized in the discussion on
policies in this study. Dupor and Liu (2003) modified Abel (1990) by measuring the utility of the “keeping up with
the Joneses” effect from the marginal consumption level. Their finding is critical and is utilized to constructing themodel of this study after its development. Liu and Turnovsky (2005) considered both macroeconomic dynamics
with consumption and production externalities as the “keeping up with the Joneses” effect in consumption andproduction functions and capital stock externalities in production. In this study, the production function that determines wages is considered a human capital externality. This externality, described as the average education level ofan economy, is designed to increase personal income. Mino (2008) developed an overlapping generations (OLG)
model with a consumption externality and demonstrated that the consumption externality fundamentally affects
both the equilibrium and the steady state characterization. Because children’s education is primarily affected byparents, the OLG economy is better for considering education. However, because the OLG economy might be toocomplicated, this study does not consider generations. These prior articles delicately developed consumption externalities, however only considered consumption externalities and not education externalities. In addition, regarding
education as consumption is incorrect because education directly and indirectly affects the entire economy.
In this study, a simple model of the education externality is developed and analyzed. The result of the analysis show that two equilibria exist that react differently to the level of productivity if an education externality is
considered. Moreover, the net marginal benefit is found to determine social preferences for education.

3

The remainder of this paper is structured as follows. The second section is devoted to describing the model,
including an education externality. The third section provides an analysis of equilibria. The fourth section develops
a social planner’s solution and discusses on policy implications. The final section concludes this paper.

2 ModelWe develop a model of education externality. The economy comprises representative household and competitive
firms.

2.1 Household
We assume that the representative household obtains utility from consumption and education. The representative
household’s utility function is as follows:u(c, e) = c + v[( e )γ
E

]
−e ,

(1)

where c represents consumption, v is a constant that represents the importance of education in utility, e denotes
the education level of the household, and E indicates the reference level of education that can be interpreted as theaverage level of education in the society. We also assume the parameter γ > 1 to account for the “keeping up with
the Joneses” effect. This effect indicates that a household increase its own education level if the education level ofother households, or the reference level, is high.
The (e/E)γ term can be interpreted as the utility from the relative education level, which reflects strictlyincreasing returns to scale. The −e term indicates the disutility from education as the effort cost. This model
assumes that the peer group unilaterally affects the household and considers exogenous and full correlated effects
from the classification by Manski (1993). Manski (1993) divided the social effects in a group into three types:
endogenous, exogenous, and correlated effects.
Two points regarding the specification of the utility function are in order. The first is that the utility function
has a quasi-linear form, for which several reasons exist. The first reason is that the function represents education
externality. A non-homothetic characteristic is required for this type of externality; moreover, Alonso-Carrera
et al. (2008) developed the restricted homothetic (RH) property and showed that the indeterminacy case does nothold the RH property. Second, we employ this specification to facilitate an evaluation of the education externality.
Dupor and Liu (2003) suggested that the externality must be measured from the marginal utility of consumption.
Therefore I added the utility function as (1) for the simple expression of the two reasons. In addition, Ljungqvist
and Uhlig (2000) uses this type quasi-linear utility function in terms of consumption externality and labor disutility.
The second point is the existence of an education externality that is determined as γ > 1. No empirical study
estimates the level of education externality. However, several empirical studies conjectured the presence of theexternality as we noted in the introduction section.
4

The household earns wages from a firm by supplying one unit of labor. The household faces the following
budget constraint:c + pe = w(e) + w,

(2)

where p represents the price of one unit of education, w(e) represents the wage that the household earns from afirm related to one’s education level, and w represents the wage that the household earns from a firm regardless ofeducation level. Therefore, the household maximizes its utility according to the budget constraint (2).

2.2 Firm
Perfectly competitive firms pay wages to workers according to their productivity. The productivity of workers isrepresented in the following equation:

Aeθ E 1−θ + w = w(e) + w,

(3)

where A is total factor productivity, and θ is a coefficient of the Cobb-Douglas production function that takes value
in the interval between 0 and 1.
The final goods produced by firms are used in consumption or in the education system. This production function
indicates that if the average level of education is low, the effect of investment in private education is weak, and viceversa. Moreover, this specification indicates that personal investment in education increases social productivity.
This relationship corresponds to secondary education rather than higher education, such as lectures at a university.
The reason for this result is that, on the one hand, education from a university can be interpreted as a signal
and may not necessarily improve a person’s ability. On the other hand, secondary education is mainly primarily
comprises learning basic skills for work, i.e., reading, writing, and calculating. Therefore, this specification is
primarily considered in the relationship between secondary education and wage and is compatible with the resultsof the empirical studies by Trostel (2004) and Moretti (2004).

2.3 Optimization problem
The representative household maximizes its own utility when accounting for the firm’s paying action. Then, by
combining equations (1), (2), and (3) and imposing non-negative conditions on e and c, the maximization problem
is as follows:

max
c,e

u(c, e) = c + v[( e )γE−e]s.t. c + pe = Aeθ E 1−θ + w,

The first-order condition of the problem is5c ≥ 0,e ≥ 0.

(4)vγeγ−1 E −γ − vE −1 = p − Aθeθ−1 E 1−θ .
Rearranging the condition, we obtainvγeγ−1 E −γ + Aθeθ−1 E 1−θ = p + v.

(5)

The non-negative condition isw ≥ pe − Aeθ E 1−θ , and e ≥ 0.
Hereafter, we assume that w is large enough to have interior solutions and we concentrate on the interior solutions
for simplicity. The left-hand side of equation (5) is the individual’s marginal benefits of education and the righthand side indicates the individual’s marginal costs of education. However, this equation cannot be solved becauseof its non-linearity, and is analyzed in the next section.

3 Analysis of equilibria
We analyze the model by dividing it into two parts. The first part is no education externality case and the second
part is the education externality case. The second part is devoted toward determining how the education externality
affects the economy. Hereafter, we concentrate on variable e because it is the determinant variable of this model.

3.1 Benchmark
First, we assume that no education externality exists, v = 0, as the benchmark of the model. We derive theequilibrium of the model. From equation (5), we obtain:Aθeθ−1 E 1−θ = p.
Solving the equation by e, we obtain the equilibrium:


1
 1−θ

 Aθ
e= 
p

E ≡ ê,θ  1−θ1 θ
c = (1 − θ)A 1−θ  
E + w.
p(6)

We compare this result with the education externality case discussed in the next subsection.

3.2 Education externality
Second, we assume that a positive education externality exists, v > 0. We derive the optimal solution but cannot
solve equation (5) in its explicit form because of its non-linearity. Therefore, we conduct a comparative statistical

6

p
LHS

RHS
2.5
p
RHS'
1.5

LHS'

`
e e

eL

e

eH

LHS and RHS mean the left-hand side and the right-hand side of (5), and LHS’ and RHS’ are those of (6).

Figure 3: The existence of equilibria: case A = 2, θ = 0.6, E = 1.5, v = 1, γ = 2, p = 1.5.
analysis on equilibria. First, we derive the condition for the two existing equilibria. If the next condition is satisfied,
we have two equilibria.
(p≡vγ(1 − θ)E

1−θ (
) γ−θ

Aθ
γ−1

γ−1
) γ−θ

(γ − θ) < p + v.

(7)

See the Appendix for a derivation of the condition. Figure 3 assists in understanding the existence of equilibria.
Condition (7) implies that some e exists that shows that the marginal benefits of education exceed the marginal
costs of education. If condition (7) is not satisfied, the marginal benefits of education are always greater thanthe marginal costs of education. Then, the optimal solution for the household is yielded as (c, e) = (+∞, +∞).
Therefore, the equilibrium does not exist.
We then assume that inequality (7) is satisfied and we define the two equilibria, eL and eH (eL < eH ), forconvenience. Hereafter, we analyze the nature of these equilibria. First, we check the stability of the equilibria.
The equilibrium eL is stable because the first-order derivative around eL of the left-hand side of equation (5) is
negative. However, the equilibrium eH is unstable because the first-order derivative around eH of the left-hand sideof equation (5) is positive. If the equilibrium eH suddenly increases, the marginal benefits overwhelm the marginal
costs. Therefore, the level of education increases to the c = 0 point. If the equilibrium eH suddenly decreases,
the level of education declines until it gets to eL . In a real economy, as Figure 1 shows the Japanese high school
enrollment rate, which has increased rapidly, is approximately 100%. Therefore, because Japan seems to be ineH equilibrium and to have deviated to increase, we should examine the eH equilibrium and discuss whether theunstable equilibrium is common in economic literature, particularly applied economics. For example, although
the saddle path in the growth theory of macroeconomics is unstable, it is frequently investigated for its economic
importance. In addition, this model does not consider time. When the parameters change, we solve other problems
and obtain other equilibria. For these reasons, the equilibria are worth investigating. We need to present the next7

lemma to clarify the range of the two equilibria.
Lemma 1. The two equilibria eL and eH exist in the range 0 < eL < e < eH , where e is the minimizing value ofthe left-hand side of the first order condition.
Proof. See the Appendix.
We obtain the following proposition by comparing the benchmark case and the education externality case.
γ−1

Proposition 1. When the condition, γ(Aθ/p) 1−θ < E, holds, eL < ê < eH is satisfied.
Proof. See the Appendix.
Proposition 1 implies that the condition that is primarily affected by the parameters E and γ is satisfied, and no
externality equilibrium ê exists between externality equilibria eL and eH . When the condition is satisfied and theequilibria eL and eH are statistically counted in the same country, the data may indicate that no externality exists
in the country even though it exists. If the condition is satisfied, the equilibrium eL represents an underinvestment
in education and the equilibrium eH represents an overinvestment in education from the no externality perspective.
γ−1

If the condition is not satisfied, then the case γ(Aθ/p) 1−θ ≥ E holds, and the relationship among eL , eH , and ê iseither eL < eH ≤ ê or ê ≤ eL < eH . The former case implies that the education externality always decreases theinvestment in education, and the latter case implies that the education externality always increases the investment
in education. However, we cannot distinguish among the two cases. We have the following proposition.
Proposition 2. For each equilibrium, the following properties hold;



deH
dwL
deL
dwH



<
0
and
<
0,
>
0
and
>0


dA
dA
dA
dA



dwH
deH
dwL
deL
= 0 and< 0,> 0 and
>0



dA
dA
dA
dA




dw
de
dwL
deL


 H > 0 and H < 0,
> 0 and
>0
dA
dA
dA
dA

if

p < p + v < p̃

ifp̃ = p + v

ifp̃ < p + v,

where p̃ is defined as follows:

p̃ ≡

γ−1
) γ−θ
1−θ (
( v ) γ−θ
Aθ

E

γ−1

1−θ

γ 1+ γ−θ .

(8)Proof. See the Appendix.
Proposition 2 states that, on the one hand, if productivity A increases, the wage and the level of education in
equilibrium eL also increase. On the other hand, when p is large enough, if A increases, the wage increases and theeducation level eH decreases. When p is not large, but is in the range of p < p < p̃, if A increases, the wage andthe level of education decrease. These suspicious movements in the education level and wages are caused by the
first-order condition (5). First, we consider the eH case. When A increases, the first term on the left-hand side of8

(5) decreases to sustain the first-order-condition, that is, decreases e. The wage is determined by wH (eH ) througha comparison of the increase in wages by A and the decrease in wages by eH . Therefore, if the former is larger
than the latter, the wage increases. If the latter is larger than the former, the wage decreases. Second, we consider
the eL case. When A increases, at eL , the household increases the education level to adjust the marginal wageequally considering the effect of utility from relative education. Therefore, at eL , an increasing A always increases
education level e. Therefore, the wage wL (eL ) always increase because an increasing A itself adds to the wages
and an increasing A indirectly affects wages through the positive relationship with e.
The economic theory predicts that the wage difference increases the high school graduation rate, as discussed
in the introduction. And the data show the predicted movement in the United States. However, the data show the
opposite movement and are not compatible with the theory in Japan. Proposition 2 theoretically explains these
movements of Japan and the United States in the same model that the theory cannot explain. In Japan, productivity
A declines as times passes.2 If we ignore the education externality term, which means that v = 0 holds, educationlevel e and wage level w also decrease. However, the data show the opposite movement. If we focus on theequilibrium eH with the p < p + v < p̃ condition, declining A induces an increasing education level eH andwage w(eH ). We interpret w(e) as the wage of high school graduates and w as the wage of only having graduatedfrom compulsory education. Therefore, the equilibrium with this condition is compatible with these movements inJapan.
In contrast, in the United States, the productivity A increases as times passes,3 and the high school graduate
s wage and graduation rate both increase. These movements are compatible with the v = 0 case and the eL
equilibrium case. Therefore we impose the equilibrium eH to represent Japan and the equilibrium eL to represent
γ−1

the United States. When the condition for Proposition 1, γ(Aθ/p) 1−θ < E, is satisfied, if we do not consider
the education externality, the United States, eL , is overeducated and Japan, eH , is undereducated, based on the
education externality case. In the next section, we examine the preferred equilibrium from the perspective of thesocial planner.

4 Social planner’s solution and policy implications
In this section, we consider the problem from the social planner’s perspective to examine how education affects thesocial welfare of the economy. In this section, we regard the reference level of education E as the personal levelof education level e .

2 This condition occurs because the growth rate of the multifactor productivity decreases from 1985 to 2011 according to the OECD statistics
database.
3 This occurrence is from the slight increase in the growth rate of multifactor productivity from 1985 to 2011 according to the OECDstatistics database.

9

4.1 Social planner’s solution
To examine how education affects the social welfare of the economy, we solve another problem regarding thereference level of education as the personal education decision. From the classification of social effects in a groupby Manski (1993), this analysis is classified as complete correlated effects, which considers the case that themembers of a group behave perfectly in the same manner. We maximize social welfare as follows:

max
c,e

u(c, e) =

 γ

e
 

c + v   − e = c + v(1 − e)e

(9)s.t. c + pe = Aeθ E 1−θ + w = Ae + w.

Solving problem (9), we obtain the next result, for which a is an arbitrary value:(w, 0)(A < p + v)(c, e) = (w, a)(A = p + v)






(+∞, +∞) (A > p + v).
The interpretation of this solution is that when A < p + v holds, the social planner does not want to invest in
education; when A = p + v holds, the planner has no intention to pursue education; and when A > p + v holds,
the planner wants to invest as much as possible in education. Therefore, we have two propositions.
Proposition 3. When A < p + v holds, the education level determined by households is always higher than that
determined by the social planner.
Proof. The proof is obvious from a comparison of the social planner’s and the household’s solution.
Proposition 4. The social preferences on equilibria eH and eL are as follows.
eH ≻ eLeH ∼ eL eH ≺ eL

A>p+v
A=p+v
A<p+v

where ≻ represents “strictly preferred to,” ∼ represents “indifferent to,” and ≺ represents “ strictly worse than.”Proof. See the Appendix.
Proposition 3 means that when A < p + v holds, that is, the financial and effort costs of education are greaterthan the unit gain from education, the social planner believes that households should not invest in education.
However, households’ investment in education is greater than zero because the marginal gains from wage and10education externalities pay for the marginal cost of education. Therefore, the planner always suffers from an
overinvestment in education.
Proposition 4 states that social preferences are determined through a comparison of productivity A and themonetary and psychological costs of education p + v. When A > p + v holds, a higher level of education isbetter for the social planner. When A = p + v holds, the social planner does not consider the level of education.
When A < p + v holds, the social planner dislikes investments in education and, therefore, prefers a lower levelof education. Normally, in a developed country, A > p + v tends to hold because productivity A is relatively highand the cost is relatively low. Therefore, the social planner prefers Japan equilibrium eH over the United States
equilibrium eL . Surely, the parameters between Japan and the United States are different. Therefore, comparing
the Japan’s equilibrium with the United States equilibrium using real data is useless. Proposition 4 insists that theUnited States can increase social welfare from the planner’s perspective by moving into eH equilibrium. However,this move may evoke reductions in large amounts of consumption, which may then reduce households’ welfare
because people in the United States might put significant weight on consumption. Therefore we must consider thispoint when considering policy implications in the next subsection.

4.2 Policy implications
Normally, in a developing country, the condition A < p + v tends to hold because productivity A is relatively
low compared with the costs p and v. In a developing country, the planner—the government—initially dislikes
investments in education. However, although the government does not want to facilitate education, households
invest in education. Finally, increasing productivity A which is caused by some exogenous factors, reverses theplanner’s preferences for education and the government facilitates investments in education. This chain of events
represents a country’s development process. Frequently, we cannot examine this theory because of a lack of
accurate developing country data on education, consumption, productivity, and so on. Therefore, further researchis required on this subject.
Moreover, we measure this economy using consumption level. The main motivation for individuals to pursue
an education is to consume more goods by earning higher wages. By rearranging the budget constraint (2), we
obtain()
c − w = e Aeθ−1 E 1−θ − p .

(10)

Solving equation (10) to equal the zero condition gives:1  1−θA ě =  
E.
p

(11)

If the equilibrium holds, ei > ě(i = H, L), then at equilibrium we consume goods less than that of the zeroeducation choice. Therefore, the following proposition is presented.

11

Proposition 5. If the following condition (12) is satisfied, then we have eL < ě < eH :  γ−11−θ γ  Av− 1
E  p < (1 − θ)p.

(12)

Proof. See the Appendix.
Proposition 5 states that, at the equilibrium eH , if condition (12) holds, then the consumption level of theequilibrium is less than that of zero education w. In this case, the level of education is relatively high and earns
higher wages than the equilibrium eL . However, the highest earned wage that is increased by education is primarily
used to obtain a higher education, and the consumption level is lowered by a higher education. This result can beinterpreted as education for education’s sake. When A > p + v holds, the planner prefers equilibrium eH andencourages households to be more educated. Therefore, the primary motivation is not achieved. To discourage
education for education’s sake, increasing productivity A seems to be a good policy. Using the results of Proposition 2, increasing A induces households to decrease the equilibrium value eH and to increase the threshold valueě. Therefore, the condition (12) is less likely to be satisfied.
These findings show that increasing productivity A is a good policy regarding both the developing economy
problem and the education for education’s sake problem. To plan and execute policies that increase productivity A,
a budget is required. Considering the government’s budget constraints, a lump-sum tax on income and a proportional tax on consumption seem to be optimal uses of financial resources for the policy to increase productivity A.
Because a proportional tax on education induces individuals to reduce education at eL equilibrium and to increase
education at eH equilibrium by increasing relative price of education p, such a tax on education e is harmful foreH equilibrium. Therefore, we must consider the equilibrium that we are in when we tax and subsidize economic
activity.

5 Conclusion
This study investigates the effects of education externality on the economy. The two education equilibria in thismodel conversely react to increasing productivity. This characteristic of the model enables us to explain the puzzling movements in Japanese education, wage, and productivity. We then determined that the parameter relationship between the productivity of firms and the price of education determines the social preferences for educationfrom the social planner’s perspective.
I now look toward the prospects of extending this model. The first possibility is to treat the reference level of
education E as an endogenous variable. In this study, the endogenous effects of the Manski (1993) classification
are ignored. The exogenous and the correlated effects are investigated in section three and four, respectively.
However, in the real world, these ideal cases are rare. Moreover, determining the reference level of education has
not been well theorized. Therefore, considering E as the endogenous variable may change the results of this model.
12Such future research may assist us in completely understanding education externality. The second possibility is toconsider dynamics. The time series graphs are shown in the introduction; however, the model does not consider
the dynamics of the economic variables. Therefore, introducing dynamics into this model may change the results.
The third, estimating the parameters, particularly v and γ, is necessary. If v is not significant, the theory collapses
and we must search for a new model to explain the suspicious movements of the variables for Japan. If γ satisfies
the condition 0 < γ ≤ 1, the model does not have two equilibria. Even though equilibrium exists, which may
increase the equilibrium level compared with the no externality case, productivity A affects e given that it has thesame sign as the no education externality case. We may have many other extensions for this model, and researchon these extensions can be fruitful.

Appendix
Existence of equilibria
First, we define the left-hand side of (5) as f (e). Second, we take the first-order derivative of f (e) by e and set
f ′ (e) = 0 to obtain:f ′ (e) = vγ(γ − 1)eγ−2 E −γ + Aθ(θ − 1)eθ−2 E 1−θ = 0.
Solving the equation for e gives us the solution, and we define the solution e as follows:[e=Aθ(1 − θ)E 1−θ+γvγ(γ − 1)

1
] γ−θ

.

Third, we prove that ē takes the minimal value of f (e). Taking the second-order derivative of f (e), we obtain:f ′′ (e) = vγ(γ − 1)eγ−3 E −γ + Aθ(θ − 1)(θ − 2)eθ−3 E 1−θ > 0,
for all e > 0. The equation indicates that ē takes the minimal value of f (e). For the existence of equilibria, wemust hold that the minimal value of the left-hand side of (5), f (ē), is smaller than the right-hand side of (5). The
condition is:
1−θ 
 γ−θ



f (ē) = vγ(1 − θ)E




γ−1
 γ−θ

 Aθ 
γ−1(γ − θ) < p + v.

Therefore, the condition is obtained.

Proof of lemma 1
From the previous discussion, e takes the minimal value of f (e). From the intermediate value theorem and thelimits of the first-order condition:

13

lim vγeγ−1 E −γ + Aθeθ−1 E 1−θ = +∞

e→+0

and

lim vγeγ−1 E −γ + Aθeθ−1 E 1−θ = +∞,e→∞there exist equilibria in the open interval (0, ē) and (ē, +∞), respectively. Because f (e) is monotonically decreasing in interval (0, ē) and its lower bound is f (ē) in interval (ē, +∞), f (e) is monotonically increasing and its lower
bound is f (ē). Therefore, 0 < eL < ē < eH holds.

Proof of proposition 1
Use (5) and (6). Arranging (5), we obtain:Aθeθ−1 E 1−θ + vγeγ−1 E −γ − p − v = 0.

(13)

To evaluate the left-hand side of (13), substitute ê into the left-hand side of (13), then to obtain the value at ê:




 γ−1
θ−1

γ  p v
 E  Aθ



− 1
.

(14)

If (14) is negative, then eL < ê < eH , which is obvious from the form of f (e) previously shown.

Proof of proposition 2First, from the proof of proposition 1, use (13) as follows:Aθeθ−1 E 1−θ + vγeγ−1 E −γ − p − v = 0.
To determine the relationship between e and A, differentiate the left-hand side of (13) by e and A to obtain:

de
dA

=−

θeθ−1 E 1−θAθ(θ − 1)eθ−2 E 1−θ + vγ(γ − 1)eγ−2 E −γ

.

(15)

The numerator always takes a positive value; therefore, the sign of de/dA depends on the denominator. We knowthat the denominator is equivalent to f ′ (e). Therefore, at the equilibrium eL , the denominator has a negative value
and de/dA > 0 holds. At eH , the denominator has a positive value and de/dA < 0 holds.
Second, because the wage is determined by w = Aeθ E 1−θ + w, we differentiate between A and e, to obtain:

14

dw
dA

= eθ E 1−θ + Aθeθ−1 E 1−θ

de
.
dA

Then, we substitute (15) into this equation to obtain:[]eθ−1 E 1−θ vγ(γ − 1)eγ−1 E −γ − Aθeθ−1 E 1−θ=.
dAAθ(θ − 1)eθ−2 E 1−θ + vγ(γ − 1)eγ−2 E −γdw

The sign of the denominator as a function of e is known because it is the same as f ′ (e). If an equilibrium exists
between 0 and ē, f ′ (e) is negative at the equilibrium. If an equilibrium is greater than ē, f ′ (e) is positive at
the equilibrium. Therefore, the sign of the numerator reveals the sign of dw/dA. The threshold value ẽ of thenumerator is determined by the following equation:vγ(γ − 1)eγ−1 E −γ − Aθeθ−1 E 1−θ = 0,
for eθ−1 E 1−θ is positive. We solve the equation by e to obtain:

1−θ+γ

1
 γ−θ

 AθE

ẽ = 

vγ(γ − 1).

1

We easily check that ẽ > ē using (1 − θ) γ−θ < 1. If an equilibrium is between 0 and ẽ, the numerator is negativeat the equilibrium. If an equilibrium is greater than ẽ, the numerator is positive at the equilibrium. Then, to obtain
the parametrized condition on ẽ, substitute ẽ into (5) to obtain the threshold parameter as follows:


γ−1 
θ−1
 γ−θ
 γ−θ
1−θ
 Aθ 
 E
p̃ ≡ 
γ 1+ γ−θ = p + v.

 
γ−1
v

From the above, we summarize the result for dw/dA as follows. At eL , the denominator and numerator are both
negative because eL < ē < ẽ. Then, we obtain dw/dA > 0. At eH < ẽ, the denominator is positive and thenumerator is negative because ē < eH < ẽ. Further, we obtain dw/dA < 0. At eH = ẽ, the denominator is 0 and
we obtain dw/dA = 0. At eH > ẽ, both the denominator and the numerator are positive because ē < ẽ < eH and
we obtain dw/dA > 0. Therefore, the proposition is proved.

Proof of proposition 4
From budget constraint (2), we obtain:c = (A − p)e + w.

15

By substituting the equation into the utility function of the social planner, the utility level is measured by (A − p −v)e + v + w. From the proof of lemma 1, eL < eH is satisfied. Therefore, when A > p + v, the social planner
prefers eH to eL . When A < p + v, the planner prefers eL to eH , and when A = p + v, education choice eH isindifferent to eL from the social planner’s perspective.

Proof of proposition 5
Write the left-hand side of (13) as follows:Aθeθ−1 E 1−θ + vγeγ−1 E −γ − p − v.
Substitute (11) into the equation to obtain:  γ−11−θ γ  Av− 1
E  p − (1 − θ)p.

References
A BEL , A. B. (1990): “Asset Prices under Habit Formation and Catching Up with the Joneses,” American Economic
Review, 80, 38–42.
A LONSO -C ARRERA , J., J. C ABALLÉ , AND X. R AURICHC (2008): “Can Consumption Spillovers be a Source of
Equilibrium Indeterminacy?” Journal of Economics of Dynamics and Control, 32, 2883–2902.
B ECKER , G. S. (1962): “Investment in Human Capital: A Theoretical Analysis,” Journal of Political Economy,
70, 9–49.
C ALVÓ -A RMENGOL , A., E. PATACCHINI , AND Y. Z ENOU (2009): “Peer Effects and Social Networks in Education,” Review of Economic Studies, 76, 1239–1267.
D UPOR , B. AND W.-F. L IU (2003): “Jealousy and Equilibrium Overconsumption,” The American Economic
Review, 93, 423–428.
H ASHIMOTO , K. AND J. A. H EATH (1995): “Income Elasticity of Educational Expenditure by Income Class: The
Case of Japanese Households,” Economics of Education Review, 14, 63–71.
L IU , W.-F. AND S. J. T URNOVSKY (2005): “Consumption Externalities, Production Externalities, and Long-run
Macroeconomic Efficiency,” Journal of Public Economics, 89, 1097–1129.
L JUNGQVIST, L. AND H. U HLIG (2000): “Tax Policy and Aggregate Demand Management Under Catching Upwith the Joneses,” The American Economic Review, 90, 356–366.

16

M ANSKI , C. F. (1993): “Identification of Endogenous Social Effects: The Reflection Problem,” The Review of
Economic Studies, 60, 531–542.
M INCER , J. (1958): “Investment in Human Capital and Personal Income Distribution,” Journal of Political Economy, 66, 281–302.
M INO , K. (2008): “Growth And Bubbles With Consumption Externalities,” The Japanese Economic Review, 59,
33–53.
M ORETTI , E. (2004): “Estimating the Social Return to Higher Education: Evidence from Longitudinal and Repeated Cross-sectional Data,” Journal of Econometrics, 121, 175–212.
T ROSTEL , P. A. (2004): “Returns to Scale in Producing Human Capital from Schooling,” Oxford Economic
Papers, 56, 461–484.

17