MINGGU
5
Elastisitas
Prepared by: INSAN HASANI
Mengukur Elastisitas
• Mengukur apakah?
• Respons atau reaksi
• Apakah alasan untuk mengetahuinya?
• Respons terhadap Permintaan dan Penawaran adalah
substansi yang menjelaskan hal-hal terkait dengan analisis
pasar.
• Mengapa tidak mengacu pada “slope” atau kemiringan?
• Sebagai pembanding antar pasar : inter market
• Sebagai pembanding didalam pasar itu sendiri: intra market
• “Slope” dapat menimbulkan kesalahpahaman
• Suatu unit pengukuran yang bebas
Mengapa “Economists” menggunakan
elastisitas
• Elastisitas adalah suatu unit pengukuran yang
bebas.
• Bukanlah suatu hal yang material
membandingkan dua pasar melalui harga dan
kuantitas dari suatu jenis barang dengan
menggunakan elastisitas.
• Elastisitas memungkinkan “economists” untuk
mengkuantifikasi perbedaan diantara pasar
tanpa menstandarisasi unit dari pengukuran.
Apakah elastisitas?
• Mengukur persentase dari perubahan satu
variabel sebagai hasil dari 1 % perubahan satu
variabel lainnya.
• Terdiri dari berbagai jenis elastisitas.
• 4 jenis yang akan dibahas.
• 3 dari fungsi permintaan
• 1 dari fungsi penawaran
2 Elastisitas Utama
• Elastisitas harga dari permintaan: kepekaan
terhadap kuantitas permintaan suatu jenis
barang sebagai akibat dari perubahan harga
dari barang tersebut.
• Elastisitas harga dari penawaran: kepekaan
terhadap kuantitas penawaran suatu jenis
barang sebagai akibat dari perubahan harga
dari barang tersebut.
• Keduanya seringkali dimaknai sebagai
elastisitas harga.
Contoh dari elastisitas harga dari
permintaan
• Ketika harga BBM meningkat 1%, kuantitas
permintaan terhadap BBM tersebut turun 0.2%,
maka permintaan bensin tidak sangat sensitif
terhadap harga.
• Elastisitas harga dari permintaan adalah -0.2 .
• Ketika harga perhiasan emas meningkat 1%,
kuantitas permintaan terhadap perhiasan emas
tersebut turun 2.6%, maka permintaan
perhiasan emas sangat sensitif terhadap harga.
• Elastisitas harga dari permintaan adalah -2.6 .
Contoh dari elastisitas harga dari
penawaran
• Ketika harga lukisan DaVinci meningkat 1%,
kuantitas penawaran terhadap lukisan tersebut tidak
berubah, maka penawaran lukisan sepenuhnya tidak
sensitif terhadap harga.
• Elastisitas harga dari penawaran adalah 0.
• Ketika harga daging meningkat 1%, kuantitas
penawaran terhadap daging tersebut meningkat 5%,
maka penawaran daging sangat sensitif terhadap
harga.
• Elastisitas harga dari penawaran adalah 5.
Contoh dari unit yang bebas dari
perbandingan …1
• Bensin dan perhiasan
• Hal tersebut bukanlah suatu masalah bahwa bensin
dijual pergalonnya $1.09 dan emas dijual per onsnya
$290.
• Kita membandingkan elastisitas permintaan dari bensin
(-0.2) dan perhiasan emas (-2.6).
• Berdasarkan elastisitas tersebut permintaan perhiasan
emas adalah lebih sensitif terhadap perubahan harga.
Contoh dari unit yang bebas dari
perbandingan …2
• Lukisan dan daging
• Hal tersebut bukanlah suatu masalah bahwa lukisan
klasik dijual perunitnya jutaan dollar sementara
daging sapi dijual per ponnya sekitar $1.50.
• Kita membandingkan elastisitas penawaran dari
lukisan klasik (0) dan daging sapi (5).
• Berdasarkan elastisitas tersebut penawaran daging
sapi lebih sensitif terhadap perubahan harga.
Relasi ekonomi inelastis
• Suatu elastisitas adalah kecil jika nilainya antara
0 dan 1 (dalam nilai absolut), kondisi tersebut
menggambarkan relasi yang inelastis.
• Inelastis permintaan adalah kuantitas permintaan
suatu jenis barang sangat tidak sensitif terhadap
perubahan harga.
• Inelastis penawaran adalah kuantitas penawaran
suatu jenis barang sangat tidak sensitif terhadap
perubahan harga.
Relasi ekonomi elastis
• Suatu elastisitas adalah besar jika nilainya lebih
besar dari 1 (dalam nilai absolut), kondisi
tersebut menggambarkan relasi yang elastis.
• Elastis permintaan adalah kuantitas permintaan
suatu jenis barang sensitif terhadap perubahan
harga.
• Elastis penawaran adalah kuantitas penawaran suatu
jenis barang sensitif terhadap perubahan harga.
Size of Price Elasticities
Unit elastic
Inelastic
0
Elastic
1
2
3
4
5
6
• Unit elastic: own price elasticity equal to 1
u
Inelastic: own price elasticity less than 1
u
Elastic: own price elasticity greater than 1
General Formula for own price
elasticity of demand
• P = Current price of good X
• XD = Quantity demanded at that price
 DP = Small change in the current price
 DXD= Resulting change in quantity demanded
Percentage Change in Quantity Demanded
Elasticity 
Percentage Change in Price
Catatan:
• Elastisitas harga dari permintaan adalah selalu
negatif.
• Elastisitas harga dari permintaan nilainya
absolut (mengabaikan tanda negatif).
• Sehingga, meskipun hasil perhitungan formula
menyebutkan bahwa elastisitas harga dari
permintaan adalah negatif, maka elastisitas
tersebut adalah 0.2 dalam contoh pertama dan
2.6 dalam contoh kedua.
Arc Formula untuk Elastisitas - Umum
• Meskipun formula eksak untuk menghitung
suatu elastisitas berguna secara teori, dalam
kenyatannya “economists” biasanya
mengunakan pendekatan untuk menghitungnya
yang disebut arc elastisitas.
• Elastisitas antara dua titik sesungguhnya
merupakan pendekatan.
• Diperlukan dua titik untuk melakukan
penghitungan.
Arc Formula for Own Price
Elasticity of Demand
• Get two points of the demand curve: Points A
and B.
• Consider PA and XA and PB and XB from the
demand relationship.
• Note: we’ll take absolute value
( X  X ) / Xavg
elasticity 
A
B
( P  P ) / Pavg
A
B
Point Formula for Own Price
Elasticity of Demand
• The exact formula for calculating an elasticity at
the point A on the demand curve.
• Note: we’ll take absolute value
A
P
elasticity 
A
X
 DX

 DP

D


at
A


Slope of the Demand Curve
 DP is the
change in
price. (DP<0)
u DX is the
change in
quantity.
u slope =
DP/ DX
u
1/slope =
DX/ DP
Price
DP
slope 
DX
Demand
P
P+ DP
DP
DX
X X + DX
Quantity
Slope Compared to Elasticity
• The slope measures the rate of change of one
variable (P, say) in terms of another (X, say).
• The elasticity measures the percentage change
of one variable (X, say) in terms of another (P,
say).
Example: Elasticity Calculation at “A”
• Slope =
(40-32)/(10-14)=-2
Linear Demand Curve
• 1/slope = -1/2
42
41
• P/X x 1/slope
= -1.5
39
38
Price
• P/X = 36/12 = 3 at
point A
40
A
37
36
35
34
33
32
• Elasticity of
demand = -1.5
• Absolute value of
the elasticity = 1.5
31
30
10
11
12
Quantity
13
14
Exercise -- Linear Demand
• Compute the
elasticity at the point
indicated in red on
the table
(X=18,P=24).
• Slope = -2
• 1/Slope = -1/2
• P/X = 24/18 = 4/3
• Elasticity = -2/3
Quantity
10
11
12
13
14
15
16
17
18
19
20
Price
40
38
36
34
32
30
28
26
24
22
20
Elasticities and Linear Demand
Linear Demand
Quantity
10
11
12
13
14
15
16
17
18
19
20
Price
Slope
40
38
36
34
32
30
28
26
24
22
20
1/Slope
-2
-2
-2
-2
-2
-2
-2
-2
-2
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
Exact
Elasticity
-1.7273
-1.5000
-1.3077
-1.1429
-1.0000
-0.8750
-0.7647
-0.6667
-0.5789
• The elasticity varies along a linear demand (or supply) curve.
This is illustrated in the linear demand curve table above.
• Note: Usually we would report last column as absolute value
Elastisitas Penawaran
• Elastisitas harga dari penawaran adalah selalu
positif.
• Elastistas harga dari penawaran merupakan
nilai sebenarnya..
• Cara yang sama digunakan untuk menghitung
formula titik dan arc pada elastisitas penawaran
sebagaimana elastisitas permintaan.
Beberapa Definisi Terkait Dengan Nilai
Ekstrim dari Elastisitas
• Economists menggunakan istilah “elastisitas
sempurna” dan “inelastis sempurna” untuk
menggambarkan nilai ekstrim dari elastisitas
harga.
• Elastisitas sempurna berarti bahwa kuantitas
(permintaan atau penawaran) sensitif terhadap
harga.
• Inelastis sempurna berarti bahwa kuantitas
(permintaan atau penawaran) tidak memiliki
sensitifitas terhadap harga.
Perfectly Elastic Demand
• We say that
demand is
perfectly elastic
when a 1%
change in the
price would result
in an infinite
change in
quantity
demanded.
Price
Perfectly Elastic Demand
(elasticity = )
Quantity
Perfectly Inelastic Demand
• We say that
demand is
perfectly inelastic
when a 1%
change in the
price would result
in no change in
quantity
demanded.
Price
Perfectly
Inelastic
Demand
(elasticity = 0)
Quantity
Perfectly Elastic Supply
• We say that
supply is perfectly
elastic when a
1% change in the
price would result
in an infinite
change in
quantity supplied.
Price
Perfectly Elastic Supply
(elasticity = )
Quantity
Perfectly Inelastic Supply
• We say that
supply is perfectly
inelastic when a
1% change in the
price would result
in no change in
quantity supplied.
Price
Perfectly
Inelastic
Supply
(elasticity = 0)
Quantity
Determinants of elasticity
• What is a major determinant of the own price
elasticity of demand?
• Availability of substitutes in consumption.
• What is a major determinant of the own price
elasticity of supply?
• Availability of alternatives in production.
Reminders
• Value of own price elasticity usually changes
along a demand curve
• there are many interesting intra elasticity applications
• Can also compare elasticities across markets
• there are interesting inter elasticity questions
Menggunakan Elastisitas Permintaan:
Total Pengeluaran/Belanja
• Total pengeluaran atas suatu produk apakah
naik atau turun ketika harga meningkat?
• Harga naik berarti lebih banyak pengeluaran
untuk masing-masing unit.
• Tetapi, kuantitas permintaan turun saat harga
naik.
• Sehingga, kita harus mengukur elastisitas harga
dari permintaan untuk menjawab permintaan
tersebut.
Contoh: Tarif Tol Jembatan
• Tarif tol jembatan the George Washington
adalah $2.00/trip.
• Andaikan kuantitas permintaan adalah 100,000
trips/hour.
• Dan elastisitas harga dari permintaan untuk
jembatan tersebut adalah 2.0, Berapakah total
pengeluaran jika tarif tol jembatan tetap dan
meningkat sebesar 10%? Bandingkan hasil
keduanya serta berikan kesimpulan!!
Bridge Toll: Elastic Demand
• Price elasticity of demand = 2.0
• Toll increase of 10% implies a 20% decline in
the quantity demanded.
• Trips fall to 80,000/hour.
• Total expenditure falls to $176,000/hour
(= 80,000 x $2.20).
• $176,000 < $200,000, the revenue from a $2.00
toll.
Contoh Tarif Tol Jembatan, Bagian 2
• Sekarang andaikan elastisitas dari permintaan
adalah 0.5.
• Bagaimana jumlah dari perjalanan dan
pengeluaran tol dipengaruhi oleh peningkatan
10% tarif tol?
Bridge Toll: Inelastic Demand
• Price elasticity of demand = 0.5
• Toll increase of 10% implies a 5% decline in the
quantity demanded.
• Trips fall to 95,000/hour.
• Total expenditure rises to $209,000/hour
(= 95,000 x $2.20).
• $209,000 > $200,000, the revenue from a $2.00
toll.
Kesimpulan:
Elastisitas dan Total Pengeluaran
• Suatu peningkatan harga akan meningkatkan
total pengeluaran, jika dan hanya jika,
elastisitas harga dari permintaan adalah
kurang dari 1, dalam nilai absolut (antara -1
dan nol)
• Inelastic demand
• Sedangkan penurunan harga akan
meningkatkan total pengeluaran, jika dan
hanya jika, elastisitas harga dari permintaan
lebih besar dari 1, dalam nilai absolut (kurang
dari -1)
• Elastic demand
Elasticity and Total
Expenditure (Graph)
•
•
At the point M, the
demand curve is unit
elastic. M is the midpoint
of this linear demand
curve
Above M, demand is
elastic, so total
expenditure falls as the
price rises
•
Below M, demand is
inelastic. so total
expenditure falls as price
falls.
•
Total expenditure is
maximized at the point M,
where the elasticity = 1.
Price
Elasticity > 1: Price reduction
increases total expenditure; price
increase reduces it.
Elasticity = 1: Total
expenditure is at a
maximum
M
Elasticity < 1:
Price reduction
reduces total
expenditure;
price increase
increases it.
Quantity
Change in Expenditure Components
• Old (price, quantity) is
(P,Q).
Price
• New (price, quantity) is
(P*,Q*).
• Expenditures increase if
G is bigger than E.
• Since the point (P,Q) is
above the midpoint of the
linear demand curve, we
know that total
expenditures will increase
at the lower price (P*,Q*).
So, E must be smaller
than G.
P
P*
E
F
G
Demand
Q
Q*
Quantity
Own price elasticity and total
revenue changes
Total revenue (TR) is price times quantity.
Along the demand curve P and Q move in
opposite directions. Knowledge of Ed
assists in knowing how TR will change.
Elasticity and total revenue relationship
When we look at the collection of consumers in the
market, at this time in our study we assume each
consumer pays the same price per unit for the product.
Also at this time in our study the total expenditure of
the consumers in the market would equal the total
revenue (TR) to the sellers.
So, here we look at the whole demand side of the
market in general.
Elasticity and total revenue relationship
P
TR in the market is
P1
equal to the price in the
market multiplied by
the quantity traded in
the market. In this
diagram TR equals the
Q area of the rectangle
Q1
made by P1, Q1 and
the horizontal and vertical axes. We know from math that
the area of a rectangle is base times height and thus here
that means P times Q.
Elasticity and total revenue relationship
We will want to look at the change in values of a
variable and in order to do so we want to have a
consistent measure of change. In this regard let’s say
the change in a variable is the later value minus the
earlier value.
Thus if the price should change from P1 to P2, then the
change in price is
P2 - P1, or similarly if the TR should change the change
in TR is TR2 - TR1.
Elasticity and total revenue
relationship
P
P1
P2
a
b c
Now in this graph
when the price is P1
the TR = a + b(adding
areas) and if the price
is P2 the TR = b + c.
Q The change in TR if
Q1 Q2
the price should fall
from P1 to P2 is (b + c) - (a + b) = c - a.
Similarly, if the price should rise from P2 to P1 the change
in TR is a - c. I will focus on price declines next.
Elasticity and total revenue
relationship
P
P1
P2
a
b c
Since the change in TR
is c - a, the value of the
change will depend on
whether c is bigger or
smaller, or even equal
to, a. In this diagram
we see c > a and thus
Q the change in TR > 0.
Q1 Q2
This means that as the price falls, TR rises. I think you
will recall that in the upper left of the demand the
demand is price elastic. Thus if the price falls in the elastic
range of demand TR rises.
Elasticity and TR
You will note on the previous screen that I had c - a. In
the graph c is indicating the change in TR because we
are selling more units. The area a is indicating the
change in TR when there is a price change. We have to
bring the two together to get the change in TR.
Thus a lower price has a good and a bad.
Good - sell more units.
Bad - sell at lower price.
Elasticity and total revenue
relationship
P
Now in this graph
when the price is P1
the TR = a + b(adding
areas) and if the price
P1
is P2 the TR = b + c.
a
P2
c
In this diagram we see
b
Q c < a and thus the
Q1 Q2
change in TR < 0.
I think you will recall that in the lower right of the
demand the demand is price inelastic. Thus if the price
falls in the inelastic range of demand TR falls.
Elasticity and total revenue
relationship
P
Now in this graph
when the price is P1
the TR = a + b(adding
P
a
areas) and if the price
1
is P2 the TR = b + c.
P
b
c
In this diagram we see
2
Q c = a and thus the
Q1 Q2
change in TR = 0.
I think you will recall that in the middle of the demand
the demand is unit elastic. Thus if the price falls in the unit
elastic range of demand TR does not change.
Elasticity and TR
P
D
Q
TR
Q
When the price falls the quantity
demanded always rises. As the
quantity demanded rises
(because of the price change)
the TR is first rising in the
elastic range, levels off when
demand is unit elastic and TR
falls in the inelastic range.
Hubungan Elastisitas Harga
dengan Total Revenue (TR)
P
• TR = P x Q
E>1 (elastis)
E=1 (uniter)
.
• Misalnya digunakan
persamaan permintaan
linear; P = a – bQ maka,
• TR = (a-bQ) x Q = aQ –bQ2
Harga
P
P
E>1
TR
TR
E=1
TR tetap
TR tetap
E<1
(inelastis)
0
E<1
TR
TR
Q
Other Price Elasticities: Cross- Price
Elasticity of Demand
• Elasticity of demand with respect to the price of a
complementary good (cross-price elasticity)
• This elasticity is negative because as the price of a
complementary good rises, the quantity demanded of
the good itself falls.
• Example (from last week) software is complementary
with computers. When the price of software rises the
quantity demanded of computers falls.
• Cross-price elasticity quantifies this effect.
Other Price Elasticities: Cross Price
Elasticity of Demand
• Elasticity of demand with respect to the price of a
substitute good (also a cross-price elasticity)
• This elasticity is positive because as the price of a
substitute good rises, the quantity demanded of the
good itself rises.
• Example (from last week) hockey is substitute for
basketball. When the price of hockey tickets rises
the quantity demanded of basketball tickets rises.
• Cross-price elasticity quantifies this effect.
Elastisitas Silang
• Kecenderungan perubahan permintaan suatu barang
disebabkan terjadi perubahan harga barang lain.
• Persamaan;
DQdx / Qx
DQdx Py
es 
atau 

DPy / Py
DPy Qx
• Elastisitas silang dapat menunjukkan hubungan 2
macam barang (komoditi) yang sifatnya;
• Substitusi, dengan koefisien (+)
• Komplementer, dengan koefisien (-)
• Barang yang tidak saling berhubungan (netral)
Other Elasticities: Income Elasticity of
Demand
• The elasticity of demand with respect to a consumer’s
income is called the income elasticity.
• When the income elasticity of demand is positive (normal good),
consumers increase their purchases of the good as their
incomes rise (e.g. automobiles, clothing).
• When the income elasticity of demand is greater than 1 (luxury
good), consumers increase their purchases of the good more
than proportionate to the income increase (e.g. ski vacations).
• When the income elasticity of demand is negative (inferior
good), consumers reduce their purchases of the good as their
incomes rise (e.g. potatoes).
Elastisitas Pendapatan
• Kecenderungan perubahan permintaan yang disebabkan oleh
perubahan pendapatan masyarakat.
• Persamaan;
DQdx / Qx
DQdx I
eI 
atau 

DI / I
DI Qx
• Misalnya, jika penghasilan konsumen meningkat 10%
permintaan barang X meningkat sebesar 15%. Koefisien
elastisitas pendapatan terhadap permintaan barang X adalah
eI 
% DQd
15%

 1,5
% DI
10%
•Barang Normal, EI positif
•Barang Superior, EI positif
•Barang Inferior, EI negatif
From Individual Supply
to Market Supply
• The supply of a good or service can be defined
for an individual firm, or for a group of firms that
make up a market or an industry.
• Market supply is the sum of all the quantities of
a good or service supplied per period by all the
firms selling in the market for that good or
service.