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Tüketici tercihini açıklamak Fayda Kavramanı açıklamak Fiyat ve gelirin önemi Optimal davranış Tüketici dengesi
Anahtar kavramlar: Homo-economicus, fayda fonksiyonu, farksızlık eğrileri, marjinal ikame oranı, bütçe Kısıtı, tüketici dengesi, gelir ikame etkisi, bireysel talep fonksiyonu
İhtiyaç ve Tüketici Tercihleri /Kavramlar
İhtitaç: Karşılandığında insanlara haz, karşılanmadığında ise elem, ve doyumsuzluk veren duygudur (açlık ve susuzluk gibi)
Mal: İnsan ihtiyaçlarını karşılayan her türlü fiziki varlık ve hizmetlerdir.
Tüketici: Mal tüketerek ihtiyaçlarını karşılayan kimsedir.
Fayda: Malların ihtiyaçları giderme özelliğidir.
İktisadi Akılcılık ve Homo-Economicus
1. Tam bilgiye sahip olma,
2. Seçici olma,
3. Çoğu aza tercih etme,
4. Tercihler arasında tutarlı olma.
Fayda Kavramı
Malların ihtiyaçlarını giderme özelliğidir.Kardinal ve ordinal yaklaşım
Fayda ölçülebilir [Jevons (1854) ve Walras (1874)]
Fayda ölçülemez [Edgeworth (1881), Antonelli (1886), İrving Fisher (1892)]
Değer paradoksu?
Fayda Fonksiyonu
There are three steps involved in the study of consumer behavior
2. Consumer Preferences To describe how and why people prefer
one good to another
3. Budget Constraints People have limited incomes
Farksızlık Eğrileri (Indifference Curves:An Example)
4010H
2010G
4030E
2040D
5010B
3020A
Units of ClothingUnits of FoodMarket Basket
The consumer prefersA to all combinations
in the yellow box, whileall those in the pink
box are preferred to A.
Farksızlık Eğrileri (Indifference Curves:An Example)
Food
10
20
30
40
10 20 30 40
Clothing
50
G
A
EH
B
D
•Indifferent between points B, A, & D•E is preferred to points on U1
•Points on U1
are preferred to H & G
Farksızlık Eğrileri (Indifference Curves:An Example)
Food
10
20
30
40
10 20 30 40
Clothing
50
U1GD
A
EH
B
Farksızlık Eğrileri(Indifference Curves)
Farksızlık eğrisi üzerindeki her nokta, eşit toplam fayda
Mal düzleminin her noktasında farksızlık eğrisi geçer
Farksızlık eğrisi negatiftir Orjine dışbükeydir
U2
U3
Farksızlık Eğrileri(Indifference Curves)
Food
Clothing
U1
ABD
Market basket Ais preferred to B.Market basket B ispreferred to D.
Farksızlık Eğrileri(Indifference Curves)
Food
Clothing •B is preferred to D•A is indifferent to B & D•B must be indifferent to D but that can’t be if B is preferred to D
U1
U1
U2
U2
A
B
D
A
B
D
EG
-1
-6
1
1
-4
-21
1
Observation: The amountof clothing given up for 1 unit of food decreasesfrom 6 to 1
Marjinal İkame Oranı (Marginal Rate of Substitution)
Food
Clothing
2 3 4 51
2
4
6
8
10
12
14
16
Marjinal İkame Oranı (Marginal Rate of Substitution)
Food2 3 4 51
Clothing
2
4
6
8
10
12
14
16 A
B
D
EG
-6
1
1
11
-4
-2-1
MRS = 6
MRS = 2
FCMRS ∆
∆−=
Azalan Marjinal İkame Oranı (Marginal Rate of Substitution)
MRS, kayıtsızlık eğrisi aşağı gittikçe azalır Along an indifference curve there is a
diminishing marginal rate of substitution (Azalan marjinal İkame eğrisi)
The MRS went from 6 to 4 to 1
Marjinal Fayda ve Tüketici Tercihi Marginal Utility and Consumer Choice
Formally:
C)( MUF) (MU CF ∆+∆=0
No change in total utility along an indifference curve. Trade off of one good to the other leaves the consumer just as well off.
Marginal Utility and Consumer Choice
Rearranging:
( )
( )
CF
CF
/MU MUMRS
saycan We
C for F of MRSFC
Since
MUMUFC
=
=∆∆−
=∆∆−
/
//
Marginal Utility and Consumer Choice
When consumers maximize satisfaction:
CF /P PMRS =
CF CF /P P /MUMU =
Since the MRS is also equal to the ratio of the marginal utility of consuming F and C
Marginal Utility and Consumer Choice
Rearranging, gives the equation for utility maximization:
CCFF PMUPMU // =
Marjinal İkame Oranı (Marginal Rate of Substitution)
Two polar cases are of interest Perfect substitutes (MRS sabit) Perfect complements (MRS=0)
Tüketici Tercihi/Kayıtsızlık Eğrisi
Orange Juice(glasses)
Apple Juice
(glasses)
2 3 41
1
2
3
4
0
Mükemmel İkame
(PerfectSubstitutes)
Tüketici Tercihi/Kayıtsızlık Eğrisi
Right Shoes
LeftShoes
2 3 41
1
2
3
4
0
Mükemmel Tamamlayıcı(Perfect
Complements)
Tüketici Tercihi( Consumer Preferences)
These consumers place a greater
value on performance than styling
Styling
Performance
Tüketici Tercihi( Consumer Preferences
These consumers place a greater
value on styling than performance
Styling
Performance
Fayda (Utility)
Utility function Formula that assigns a level of utility to
individual market baskets If the utility function is
U(F,C) = F + 2CA market basket with 8 units of food and 3 units of
clothing gives a utility of
14 = 8 + 2(3)
Utility - Example
4 + 2(4) = 1244C
6 + 2(4) = 1446B
8 + 2(3) = 1438A
UtilityClothing FoodMarket Basket
Consumer is indifferent between A & B and prefers both to C
Utility - Example
Baskets for each level of utility can be plotted to get an indifference curve To find the indifference curve for a utility of
14, we can change the combinations of food and clothing that give us a utility of 14
Utility - Example
Food10 155
5
10
15
0
Clothing
U1 = 25
U2 = 50
U3 = 100A
B
C
Basket U = FC C 25 = 2.5(10) A 25 = 5(5) B 25 = 10(2.5)
ICPFPCF =+
Bütçe Doğrusu (The Budget Line)
The budget line then can be written:
All income is allocated to food (F) and/or clothing (C)
Bütçe Doğrusu (The Budget Line)
Different choices of food and clothing can be calculated that use all income These choices can be graphed as the budget
line
Example: Assume income of $80/week, PF = $1 and PC
= $2
Bütçe Kısıtı(Budget Constraints)
$80080G
$801060E
$802040D
$803020B
$80400A
IncomeI = PFF + PCC
Clothing
PC = $2
Food
PF = $1
Market Basket
C
F
P
P
F
C Slope -
2
1- ==
∆∆=
Bütçe Doğrusu (The Budget Line)
10
20
A
B
D
E
G
(I/PC) = 40
Food40 60 80 = (I/PF)20
10
20
30
0
Clothing
Bütçe Doğrusu Değişimi(The Budget Line – Changes)
An increase inincome shifts
the budget lineoutward
Food(units per week)
Clothing(units
per week)
80 120 16040
20
40
60
80
0
(I = $160)L2
(I = $80)L1
L3
(I =$40)
A decrease inincome shifts
the budget lineinward
Fiyat Değişiminin Etkisi (The Effects of Changes in Prices)
The Effects of Changes in Prices If the price of one good decreases, the
budget line shifts outward, pivoting from the other good’s intercept.
If the price of food decreases and you buy only food (x-intercept), then you can buy more food. The x-intercept shifts out.
If you buy only clothing (y-intercept), you can buy the same amount. No change in y-intercept.
Fiyat Değişiminin Etkisi (The Effects of Changes in Prices)
(PF = 1)
L1
An increase in theprice of food to$2.00 changesthe slope of thebudget line androtates it inward.L3
(PF = 2)(PF = 1/2)
L2
A decrease in theprice of food to$.50 changes
the slope of thebudget line and
rotates it outward.
40Food(units per week)
Clothing(units
per week)
80 120 160
40
Tüketici Tercihi (Consumer Choice)
Given preferences and budget constraints, how do consumers choose what to buy?
Consumers choose a combination of goods that will maximize their satisfaction, given the limited budget available to them
Tüketici Tercihi (Consumer Choice)
The maximizing market basket must satisfy two conditions:
2. It must be located on the budget line They spend all their income – more is better
3. It must give the consumer the most preferred combination of goods and services
Tüketici Tercihi (Consumer Choice)
Graphically, we can see different indifference curves of a consumer choosing between clothing and food
Remember that U3 > U2 > U1 for our indifference curves
Consumer wants to choose highest utility within their budget
Tüketici Tercihi (Consumer Choice)
U3
D
U2
C
Food (units per week)40 8020
Clothing(units per
week)
20
30
40
0
U1
A
B
•A, B, C on budget line•D highest utility but not affordable•C highest affordable utility•Consumer chooses C
Tüketici Tercihi (Consumer Choice)
Consumer will choose highest indifference curve on budget line
In previous graph, point C is where the indifference curve is just tangent to the budget line
Slope of the budget line equals the slope of the indifference curve at this point
Tüketici Tercihi (Consumer Choice)
Recall, the slope of an indifference curve is:
F
CMRS
∆∆−=
C
F
P
PSlope −=
Further, the slope of the budget line is:
Tüketici Tercihi (Consumer Choice)
Therefore, it can be said at consumer’s optimal consumption point,
y
C
F
P
PxMRS
P
PMRS
=
=
Tüketici Tercihi (Consumer Choice)
It can be said that satisfaction is maximized when marginal rate of substitution (of F and C) is equal to the ratio of the prices (of F and C)
Note this is ONLY true at the optimal consumption point
Tüketici Tercihi (Consumer Choice)
Optimal consumption point is where marginal benefits equal marginal costs
MB = MRS = benefit associated with consumption of 1 more unit of food
MC = cost of additional unit of food 1 unit food = ½ unit clothing
PF/PC
Tüketici Tercihi (Consumer Choice)
If MRS ≠ PF/PC then individuals can reallocate basket to increase utility
If MRS > PF/PC
Will increase food and decrease clothing until MRS = PF/PC
If MRS < PF/PC
Will increase clothing and decrease food until MRS = PF/PC
Tüketici Tercihi (Consumer Choice)
Food (units per week)
Clothing(units per
week)
40 8020
20
30
40
0
Point B does not maximize satisfaction
because theMRS = -10/10 = 1
is greater than the price ratio = 1/2
+10F U1
-10C
B
Consumer Choice: An Application Revisited
Consider two groups of consumers, each wishing to spend $10,000 on the styling and performance of a car
Each group has different preferences
Consumer Choice: An Application Revisited
Styling
Performance$10,000
$10,000 These consumerswant performance
worth $7000 and styling worth $3000
$3,000
$7,000
Consumer Choice: An Application Revisited
These consumers want styling worth
$7000 and performance worth
$3000
$3,000
$7,000
Styling
$10,000
$10,000
Performance