1. Fundamental Concepts & Basic Framework of Demand and Supply:
Prof. Samar K. Datta
Session 1
28th June, 2007

2. Materials intended to be covered in this session
Objectives of EA – fundamentals of microeconomic analysis
Concerns of micro & macro-economics
Race between human wants & scarcity of economic resources giving rise to the fundamental economic choice problem
Functions of an economic system – role of prices, government & institutions
Notion of market
The demand side
Law of demand
Factors affecting demand
Features of a market demand curve
Movement along & off (i.e., shift of) the demand curve
The supply side
Law of supply
Factors affecting supply
Features of a supply curve
Movement along & off the supply curve
Price determination through interaction between demand & supply
Existence & stability of equilibrium
Shifts in demand & supply
Concepts of point & arc elasticity; Price, income & cross elasticity of demand; Certain properties of elasticity
Some applications & food for thought

3. Objectives of EA etc. Why EA dealing with micro-economics?
Perhaps the most important component of any business analysis, providing clues towards answering a whole lot of questions;
Provides insights thro’ analysis of decision-making process by economic agents and their interaction with the market
Provides basis for a number of applied fields in management
Distinctive feature of micro-economics vis-à-vis macro-economics:
Macro dealing with behavior of aggregative variables like price, income, employment, money supply, exchange rate etc.

4. Fundamental issue & methodology used
Race between human wants & scarce economic resources – land, labor, capital and entrepreneurial skill
Example, asking a poor man about his demand for credit: why does he specify his demand as a very large number, a small number & even a zero, depending upon how we pose the question? What are his wants and demand?
Broad methodology used:
Marginal analysis;
Positive rather than normative analysis;
Trade off involved in most choices
Question: Why heath care expenses increasing steadily in the US?

5. Functioning of an economic system
Role of prices in resolving issues like what to produce & for whom to produce (i.e., issues on marketing), how to produce (i.e., issues on technology & institutions)
Role of prices (interest, wages, rent, profit etc.) in fostering economic growth
Can prices ensure rationing over time & achieve sustainability?
Is there any role for government and other institutions?

6. The Market
A market is an institutional arrangement under which buyers and sellers can voluntarily exchange some quantity of a good or service at a mutually agreeable price.
It can, but need not be a specific place or location where buyers and sellers actually come face to face for the purpose of transacting their business – e.g. market for professors has no physical location

7. The Concept of Demand
Human wants are all the goods, services, and conditions of life that individuals desire (i.e., has use value)
Demand in economics is want backed by purchasing power (note difference between effective demand and notional demand)
A consumer’s claim on a good/service is recognized by the producer only if it is backed by sufficient purchasing power

8. Law of Demand & the Market Demand Curve
Other things remaining the same, the quantity demanded of a commodity is inversely related to its price.
A lower price may encourage existing consumers to consume larger quantities
Also, other consumers who were previously unable to afford the commodity may now begin consuming it
The market demand curve
refers to the behavior of an aggregate of economic agents
over a given period of time
while holding constant all other relevant economic variables on which demand depends (ceteris paribus assumption)
On the presumption that different units of the commodity are homogeneous (else weights of product composition to be taken into consideration)

9. Example: Demand For Ice Cream
Price of Ice Cream
Interpret points above
& below the demand curve
Q(d) = f(P)
Quantity of Ice Cream 9

10. Ceteris Paribus . . .
...implies that all the relevant variables (e.g. determinants of demand) are held constant, except the one(s) being studied at the time. Among other variables held constant are consumers’ incomes, tastes and preferences, prices of related commodities (substitutes and complements), number of consumers in the market, weather, future expectations, etc. 18

11. Determinants of Demand
Market Price
Consumer Income
Prices of Related Goods
Tastes
Expectations
Number of Consumers 11

12. Determinants of Demand: Market Price
Law of Demand:
There exists an inverse relationship between Price and Quantity Demanded. Q 12

13. Determinants of Demand: IncomeP
As income increases, the demand for a normal good will increase. Q 13

14. Determinant of Demand: IncomeP
As income increases, the demand for an inferior good decreases (e.g., in case of coarse cereals). Q 14

15. Determinants of Demand: Prices of Related Goods
When the fall in price of one good reduces the demand for another good, the two goods are substitutes. 15

16. Determinants of Demand: Prices of Related Goods
When the fall in price of one good increases the demand for another good, the two goods are complements. 16

17. Advertisement, for example, may shift up demand.
Determinants of Demand: Tastes & preferences, consumer expectations of future income & price
Advertisement, for example, may shift up demand.
Expectations of future income rise or price rise may shift up current demand.

18. Demand function general form
Qx = function of
Px (own price) (-)
Pz (price of related goods) (+/-)
Y (consumer income) (+/-)
N (size of population) (+)
α (tastes/preferences) (+/-)
Pe/P or Ye/Y (expectations about future price or income) (+/-)

19. Demand Schedule and Demand Curve
A table that shows the relationship between the price of the good and the quantity demanded
Qx Px
50 2
20 3
Demand Curve:
The downward-sloping line relating price and quantity demanded 17

20. Movements vs. Shifts in the Demand Curve
Change in Quantity Demanded
Movement along the demand curve caused by a change in the market price of the product.
Change in Demand
A shift in the demand curve, either to the left or right i.e. a change in the quantity demanded at each commodity price
The demand curve shifts when there is a change in (a) consumers’ incomes, (b) tastes and preferences, (c) prices of related commodities, and (d) number of consumers in the market, etc. 19

21. Changes in Quantity Demanded
Price
$2.00
$1.00
Quantity 7 13 21

22. Change in Demand
Price
$2.00
Quantity 7 10 23

23. GEOMETRIC FEATURES OF A DEMAND CURVE
Its level, depending on role of non-price factors (interpret intercepts on both axes)
Its shape – i.e., inverse relationship, decided by law of demand
Its slope, is decided by units of P & Q (the curve becoming flatter with rise in unit of Q or P), the reference period (usually flatter in long run), & role of non-price factors (e.g., flatter for luxury goods)
Its curvature – can be concave, convex, straight line or a combination (theory proving no further clue)
If you can delay the buying (Car) then flatter in short run.
If you can not delay the buying (Gasoline) then flatter in long run.

24. The Concept of Supply. P
Quantity Supplied refers to the amount (quantity) of a good that sellers are willing and able to make available for sale at alternative prices in a given point in time. Interpret points above & below the supply curve
Q(s) = f(P) Q 25

25. Determinants of Supply
Market price (+)
Input prices (-)
Cheaper technology (+)
Price of alternative goods (-)
Government tax (-) or subsidy (+)
Expectations of future price rise (-)
Number of Producers (+) 27

26. Determinant of Supply: Market Price
Law of Supply
There exists an direct (positive) relationship between Price and Quantity Supplied. Q 28

27. Interpreting features of a supply curve
Level/intercept
Direction
Slope
Curvature

28. Change in quantity supplied verses change in supply
Movement along the supply curve, caused by a change in the market price of the product.
Change in Supply
A shift in the supply curve, either to the left or right. 30

29. Supply: Schedule and Curve
A table that shows the relationship between the price of the good and the quantity supplied.
Supply Curve
The upward-sloping line relating price and quantity supplied. 29

30. Changes in Quantity Supplied
Price
$2.00
$1.00
Quantity 1 7 32

31. Change in Supply
Price
$2.00
Quantity 7 11 34

32. Supply and Demand Together
Equilibrium Price is one at which the supply and demand curve intersect (i.e., D=S) (assimilating interests of two conflicting groups thro’ negotiation & adjustment in terms of price)
Generally, there is one stable equilibrium, as shown in next slide.
However, adjustments may not always lead to a stable equilibrium (i.e., convergence).
Moreover, there may be multiple equilibrium, some of which may not be fully stable, as we shall see shortly.

33. Forces of Demand and Supply At Rest Market Equilibrium
Price
$2.00
Quantity 7 39

34. Actions of buyers and sellers that move toward equilibrium.
Excess Supply
Price is above equilibrium price, therefore producers are unable to sell all they want at the going price.
Excess Demand
Price is below equilibrium price, therefore consumers are unable to buy all they want at the going price. 40

35. Actions of buyers and sellers that move toward equilibrium.
Price
Excess Supply
Quantity 42

36. Actions of buyers and sellers that move toward equilibrium.
Price
Excess
Demand
Quantity 44

37. Stability of Market Equilibrium
The backward bending supply curve of labor may cause multiple equilibrium - some unstable (e.g. at A), some stable (e.g., at B).

38. Comparative Statics: Analyzing Changes in Equilibrium
Determine if event shifts supply curve, the demand curve, or both.
Determine if curve(s) shift to left or right.
Determine how shift affects equilibrium price and quantity.
Example: Demand for ice cream given hot weather. 45

39. Change in demand for ice cream due to hot weather
Price
New
Equilibrium Pe Pe
Quantity Qe Qe 49

40. A point to note
For analytical convenience, an artificial dichotomy is created between producers and consumers; and demand and supply
Very often in the real world, producers and consumers are either
the same person e.g. a farmer who eats his own crop, or
play both roles simultaneously – a person who produces one product, consumes others
Also, demand and supply may be dependent on each other – e.g. generation of income during production may expand the customer base for the product e.g. workers in Ford buying the Ford motor car.

41. Price Elasticity of Demand
Price elasticity of demand measures the percentage change in the quantity demanded resulting from a 1-percent change in price.

42. Price Elasticity and Consumer Expenditure
Demand If Price Increases, If Price Decreases,
Expenditures: Expenditures:
Elastic goods: luxury
Inelastic goods: necessity
Inelastic (Ep <1) Increase Decrease
Unit Elastic (Ep = 1) Unchanged Unchanged
Elastic (Ep >1) Decrease Increase

43. Point Elasticity of Demand
Point elasticity measures elasticity at a point on the demand curve.
Its formula is:

44. Variation in Point Elasticity over a Linear Demand Curve

45. Elastic vs. Inelastic Demand Curves

46. Problems Using Point Elasticity
We may need to calculate price elasticity over portion of the demand curve rather than at a single point.
The price and quantity used as the base will alter the price elasticity of demand (point elasticity of demand is not symmetric).

47. Arc Elasticity of Demand
Arc elasticity calculates elasticity over a range of prices
Its formula is:

48. Income Elasticity of Demand
Income elasticity of demand measures the percentage change in the quantity demanded resulting from a 1-percent change in income.
Its formula is:

49. Income Elasticity of Demand and type of Good
Positive
0 < e < 1
e > 1
Negative
Type of Good
Normal Good
Necessity
Luxury
Inferior Good

50. Cross-price Elasticity of Demand
Cross-price elasticity of demand measures the percentage change in the quantity demanded of good Y resulting from a 1-percent change in price of good X.
Its formula is:

51. Cross-Price Elasticity of Demand and type of Good
Positive
Negative
Type of good
Substitutes
Complements

52. Some applications & food for thought
How to cut down cigarette smoking ?
Does minimum wages really help the workers ?
Why is rent control often found to create more shortage of urban housing ?
Why do we often observe greater wage inequality between unskilled and skilled workers ?
Why is coffee price found declining, whereas Nestle and coffee shops are found to be making huge profits ?
Why is long run price of natural resources like copper declining in spite of the fact that it is exhaustible ?
Why did average rental price fall in NY Mahattan following 9/11, 2001?

53. Some applications & food for thought
Why and how does imposition of price ceiling (rationing) on an essential item often lead to emergence of a black market in that good?
Although in general longer run supply curves are flatter as compared to their shorter run counterparts, why do we then often observe a reversal in case of supply of secondary copper (i.e., new supply based on scrap copper), for example?
Why is demand curve for gasoline flatter in the long-run, but steeper in the short-run, while the opposite is true for automobiles?
For what type of products the long-run supply curve is steeper as compared to its short-run counterpart?
(answer in terms of the basic supply-demand framework and shifts in one or both curves)