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 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 1.Consumer Preferences To describe how and why people prefer one good to another 2.Budget Constraints People have limited incomes
Farksızlık Eğrileri (Indifference Curves:An Example) Market BasketUnits of FoodUnits of Clothing A2030 B1050 D4020 E3040 G1020 H1040
The consumer prefers A to all combinations in the yellow box, while all those in the pink box are preferred to A. Farksızlık Eğrileri (Indifference Curves:An Example) Food 10 20 30 40 10203040 Clothin g 50 G A EH B D
Indifferent between points B, A, & D E is preferred to points on U 1 Points on U 1 are preferred to H & G Farksızlık Eğrileri (Indifference Curves:An Example) Food 10 20 30 40 10203040 Clothin g 50 U1U1 G D A E H 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
U2U2 U3U3 Farksızlık Eğrileri (Indifference Curves) Food Clothing U1U1 A B D Market basket A is preferred to B. Market basket B is preferred 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 U1U1 U1U1 U2U2 U2U2 A B D
A B D E G -6 1 1 -4 -2 1 1 Observation: The amount of clothing given up for 1 unit of food decreases from 6 to 1 Marjinal İkame Oranı (Marginal Rate of Substitution) Food Clothing 23451 2 4 6 8 10 12 14 16
Marjinal İkame Oranı (Marginal Rate of Substitution) Food 23451 Clothing 2 4 6 8 10 12 14 16 A B D E G -6 1 1 1 1 -4 -2 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)
Tüketici Tercihi/Kayıtsızlık Eğrisi Orange Juice (glasses) Apple Juice (glasses) 2341 1 2 3 4 0 Mükemmel İkame (Perfect Substitutes)
Tüketici Tercihi/Kayıtsızlık Eğrisi Right Shoes Left Shoes 2341 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 + 2C A market basket with 8 units of food and 3 units of clothing gives a utility of 14 = 8 + 2(3)
Utility - Example Market Basket FoodClothingUtility A838 + 2(3) = 14 B646 + 2(4) = 14 C444 + 2(4) = 12 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 Food 10155 5 10 15 0 Clothing U 1 = 25 U 2 = 50 U 3 = 100 A B C BasketU = FC C25 = 2.5(10) A25 = 5(5) B25 = 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, P F = $1 and P C = $2
Bütçe Kısıtı(Budget Constraints) Market Basket Food P F = $1 Clothing P C = $2 Income I = P F F + P C C A040$80 B2030$80 D4020$80 E6010$80 G800$80
Bütçe Doğrusu (The Budget Line) 10 20 A B D E G ( I/P C ) = 40 Food 4060 80 = ( I/P F ) 20 10 20 30 0 Clothing
Bütçe Doğrusu Değişimi (The Budget Line – Changes) An increase in income shifts the budget line outward Food (units per week) Clothing (units per week) 8012016040 20 40 60 80 0 ( I = $160) L2L2 ( I = $80) L1L1 L3L3 ( I = $40) 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.
Fiyat Değişiminin Etkisi (The Effects of Changes in Prices) ( P F = 1) L1L1 An increase in the price of food to $2.00 changes the slope of the budget line and rotates it inward. L3L3 ( P F = 2) ( P F = 1/2) L2L2 A decrease in the price of food to $.50 changes the slope of the budget line and rotates it outward. 40 Food (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: 1.It must be located on the budget line They spend all their income – more is better 2.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 U 3 > U 2 > U 1 for our indifference curves Consumer wants to choose highest utility within their budget
Tüketici Tercihi (Consumer Choice) U3U3 D U2U2 C Food (units per week) 408020 Clothing (units per week) 20 30 40 0 U1U1 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: 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 P F /P C
Tüketici Tercihi (Consumer Choice) If MRS ≠ P F /P C then individuals can reallocate basket to increase utility If MRS > P F /P C Will increase food and decrease clothing until MRS = P F /P C If MRS < P F /P C Will increase clothing and decrease food until MRS = P F /P C
Tüketici Tercihi (Consumer Choice) Food (units per week) Clothing (units per week) 408020 30 40 0 Point B does not maximize satisfaction because the MRS = -10/10 = 1 is greater than the price ratio = 1/2 +10 F U1U1 -10 C 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 These consumers want 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 Performance