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2. BÖLÜM. TÜKETİCİ TERCİHLERİ ( Consumer Preferences ). Amaçlarımız. Tüketici tercihini açıklamak Fayda Kavramanı açıklamak Fiyat ve gelirin önemi Optimal davranış Tüketici dengesi
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2. BÖLÜM TÜKETİCİ TERCİHLERİ (Consumer Preferences)
Amaçlarımız • 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 • Tam bilgiye sahip olma, • Seçici olma, • Çoğu aza tercih etme, • 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 • Consumer Preferences • To describe how and why people prefer one good to another • Budget Constraints • People have limited incomes
B 50 Clothing H E 40 A 30 D G 20 10 Food 10 20 30 40 Farksızlık Eğrileri (Indifference Curves:An Example) The consumer prefers A to all combinations in the yellow box, while all those in the pink box are preferred to A.
B 50 Clothing H E 40 A 30 D 20 G U1 10 Food 10 20 30 40 Farksızlık Eğrileri (Indifference Curves:An Example) • Indifferent between points B, A, & D • E is preferred to points on U1 • Points on U1are preferred to H & G
Farksızlık Eğrileri(Indifference Curves) • Farksızlık eğrisi üzerindeki her nokta, eşit toplam fayda • Mal düzleminin her noktasında farksızlık eğrisi geçer • Farksızlık eğrisi negatiftir • Orjine dışbükeydir
Clothing D B A U3 U2 U1 Food Farksızlık Eğrileri(Indifference Curves) Market basket A is preferred to B. Market basket B is preferred to D.
U1 U2 Clothing A B U2 D U1 Food Farksızlık Eğrileri(Indifference Curves) • 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
A 16 Clothing 14 12 -6 B 10 1 8 -4 D 6 E 1 G -2 4 1 -1 1 2 Food 1 2 3 4 5 Marjinal İkame Oranı(Marginal Rate of Substitution) Observation: The amount of clothing given up for 1 unit of food decreases from 6 to 1
A Clothing 16 14 -6 12 B 10 1 -4 8 D 1 6 E -2 G 4 1 -1 1 2 Food 1 2 3 4 5 Marjinal İkame Oranı(Marginal Rate of Substitution) MRS = 6 MRS = 2
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: 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:
Marginal Utility and Consumer Choice • When consumers maximize satisfaction: 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:
Marjinal İkame Oranı(Marginal Rate of Substitution) • Two polar cases are of interest • Perfect substitutes (MRS sabit) • Perfect complements (MRS=0)
Apple Juice (glasses) 4 3 2 1 Orange Juice (glasses) 0 1 2 3 4 Tüketici Tercihi/Kayıtsızlık Eğrisi Mükemmel İkame (Perfect Substitutes)
Left Shoes 4 3 2 1 0 1 2 3 4 Right Shoes Tüketici Tercihi/Kayıtsızlık Eğrisi Mükemmel Tamamlayıcı (Perfect Complements)
Styling Performance 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
Fayda (Utility) • Utility function • Formula that assigns a level of utility to individual market baskets • If the utility function is U(F,C) = F + 2C A market basket with 8 units of food and 3 units of clothing gives a utility of 14 = 8 + 2(3)
Utility - Example 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
Clothing 15 C 10 U3 = 100 A 5 B U2 = 50 U1 = 25 Food 0 5 10 15 Utility - Example Basket U = FC C 25 = 2.5(10) A 25 = 5(5) B 25 = 10(2.5)
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
Clothing (I/PC) = 40 A B 30 10 D 20 20 E 10 G Food 0 20 40 60 80 = (I/PF) Bütçe Doğrusu (The Budget Line)
Clothing (units per week) 80 60 L2 (I = $160) 40 20 L3 L1 (I = $40) Food (units per week) (I = $80) 0 40 80 120 160 Bütçe Doğrusu Değişimi(The Budget Line – Changes) An increase in income shifts the budget line outward A decrease in income shifts the budget line inward
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.
Clothing (units per week) 40 L2 L1 L3 (PF = 1/2) (PF = 1) Food (units per week) (PF = 2) 80 160 120 40 Fiyat Değişiminin Etkisi (The Effects of Changes in Prices) A decrease in the price of food to $.50 changes the slope of the budget line and rotates it outward. An increase in the price of food to $2.00 changes the slope of the budget line and rotates it inward.
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: • It must be located on the budget line • They spend all their income – more is better • 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
Clothing (units per week) 40 A D 30 C 20 U3 U2 U1 B 0 20 40 80 Food (units per week) Tüketici Tercihi (Consumer Choice) • 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: Further, the slope of the budget line is:
Tüketici Tercihi (Consumer Choice) • Therefore, it can be said at consumer’s optimal consumption point,
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
Clothing (units per week) 40 B 30 -10C 20 +10F U1 0 20 40 80 Food (units per week) Tüketici Tercihi (Consumer Choice) Point B does not maximize satisfaction because the MRS = -10/10 = 1 is greater than the price ratio = 1/2
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