alevel economics 基础 讲义ppt课件

1、.,A-LEVEL Microeconomics basic,.,2,1 What is Economics about?The problem of scarcity,Economics is the study of how society chooses to allocate its scarce resources to the production of goods and services in order to satisfy unlimited wants.,.,Human wants are unlimited, but Resources are limited (sca

2、rce) A central problem therefore existswe call this the problem of SCARCITY,.,4,3 Definition of economics,Economics is the study of societys decisions about production consumption allocation of scarce resources in order to satisfy as many unlimited wants as possible.,.,5,4 Two branches of economics,

3、Microeconomics is the branch of economics that studies decision-making by a single individual, household, firm, industry or level of government. Macroeconomics is the branch of economics that studies decision-making for the economy as a whole.,.,6,5 Macroeconomic Issues,aggregate demand, aggregate s

4、upply economic growth unemployment inflation balance of trade exchange rates,.,7,6 Microeconomic Issues,demand and supply decisions of what to produce, how to produce, for whom to produce the concept of opportunity cost based on comparing what you have decided vs what is the next best alternative yo

5、u have given up rational decision making based on cost vs benefit; best value for money weighing up marginal costs and marginal benefits based on comparing the extra benefit with the extra cost the social implications of choice society i.e. taking into consideration how a certain choice may have an

6、indirect cost on,. 2007 Pearson Education Australia,Resources,Resources are the basic categories of inputs used to produce goods and services. Resources can also be called the factors of production.,. 2007 Pearson Education Australia,Three categories of resources,Land Labour Capital,. 2007 Pearson E

7、ducation Australia,Resources: land,Any natural resource provided by nature used in the process of production For example: forests, minerals, wildlife, oil, rivers, lakes, oceans May be renewable or non-renewable,. 2007 Pearson Education Australia,Resources: labour,The mental and physical capacity of

8、 workers to produce goods and services For example: farmers, nurses, lawyers Entrepreneurship is a special type of labour the creative ability of individuals to manage the combination of resources to produce products.,. 2007 Pearson Education Australia,Entrepreneurship,Organises and manages the reso

9、urces needed to produce goods and services,. 2007 Pearson Education Australia,Resources: capital,Capital is the physical plant, machinery and equipment used to produce other goods. That is, human-made goods that do not directly satisfy human wants, for example: Earlier: axe, bow and arrow Now: build

10、ings, production equipment, software, factories.,. 2007 Pearson Education Australia,A note about financial capital,Economists do not include money in their definition of capital money simply gives a measure to the value of assets.,. 2007 Pearson Education Australia,Opportunity cost,The best alternat

11、ive sacrificed for a chosen alternative Opportunity cost applies to personal, group and national decision-making, for example What could you be doing if you were not currently studying? How many new roads have to be forgone if the government spends tax revenues on homeland security?,. 2007 Pearson E

12、ducation Australia,Marginal analysis,Marginal analysis examines how the costs and benefits change in response to incremental changes in actions. Any additional action by an individual or a firm, such as buying an additional pair of shoes or increasing production of a product by an additional unit, b

13、rings additional cost. The central question in marginal analysis is whether the expected benefits of that action exceed the added cost,. 2007 Pearson Education Australia,Marginal analysis,Marginal analysis helps businesses and individuals balance the costs and benefits of additional actions-whether

14、to produce more, consume more, or other decisions-and determine whether the benefits will exceed costs, thus increasing utility.,. 2007 Pearson Education Australia,Marginal analysis,Marginal analysis benefits government policy makers, as well. Weighing the costs and benefits can help government offi

15、cials determine if allocating additional resources to a particular public program will generate additional benefits for the general public,. 2007 Pearson Education Australia,Short-Run v Long Run,Short-Run: A time period in which at least one factor of production is fixed (i.e. cannot increase its am

16、ount) it is not defined in terms of number of days/weeks) Long Run: A time period long enough for all inputs to be varied It is not a defined period of time;,. 2007 Pearson Education Australia,Cost concepts,Total fixed costs are costs that do not vary as output varies and must be paid even if output

17、 is zero. Total variable costs are costs that are zero when output is zero and vary as output varies. Total cost is the sum of fixed cost and variable cost. TC = TFC + TVC,. 2007 Pearson Education Australia,Total costs,Note: The x and y axis units here are unrelated to the previous diagram,. 2007 Pe

18、arson Education Australia,Average cost concepts,Average fixed cost (AFC) total fixed cost divided by the quantity of output produced: Average variable cost (AVC) total variable cost divided by the quantity of output produced:,AFC = TFC,AVC = TVC,Q,Q,. 2007 Pearson Education Australia,Average total c

19、ost,Total cost divided by the quantity of output produced,ATC = AFC + AVC = TC,Q,. 2007 Pearson Education Australia,Marginal cost,Measures how much total cost increases when an additional unit of output is produced. MC : the change in total cost when one extra unit of output is produced,MC = TC = TV

20、C,Q,Q,. 2007 Pearson Education Australia,Total costs,. 2007 Pearson Education Australia,Inverse relationship: MP the firm will need to decide about the scale of its operation and the production techniques that it uses; these decisions will affect production costs so it is important to get these deci

21、sions right.,. 2007 Pearson Education Australia,Relation between LRAC and SRAC Curves,A firm with just one factory and faces SRAC curve (following diagrams); In the long-run it can build more factories and experiences economies of scale due to administrative savings, each successive factory will all

22、ow it to produce with a new lower SRAC curve; Thus with 2 factories it will have curve SRAC2 and with three then SRAC3, and so on; Each SRAC curve corresponds to a particular amount of the factor that is fixed in the short-run (in this case the factory); There are many SRAC curves as many different

23、factories of different sizes or extensions to existing one could be made. The LRAC curve is an ENVELOPE CURVE,. 2007 Pearson Education Australia,Costs,Output,O,Examples of short-run average cost curves,SRAC2,SRAC3,SRAC4,SRAC5,Constructing a Long-run Average Cost Curve from Short-run Average Cost Cur

24、ves,. 2007 Pearson Education Australia,LRAC,Costs,Output,O,SRAC5,SRAC4,SRAC3,SRAC2,Constructing a Long-run Average Cost Curve from Short-run Average Cost Curves,. 2007 Pearson Education Australia,Scales of production,The long-run average cost curve is U-shaped. This reflects returns to scale three t

25、ypes are recognised: Economies of scale (LRAC falls as output rises) Constant returns to scale Diseconomies of scale (LRAC rises as output rises).,. 2007 Pearson Education Australia,Scales of production,. 2007 Pearson Education Australia,Economies of scale,A situation in which the long-run average c

26、ost curve declines as the firm increases output Sources of economies of scale: Specialisation and Division of Labour Greater efficiency of larger machines (eg combine harvester, super photocopier. Eg machine A costs $1000 eliminate duplication) Financial economies (bulk discounts) Economies of Scope

27、 (producing a range of products may increase sales and spread out overheads Eg: CD, DVD, players, amplifiers etc vs only CD) (Refer to Sloman p87,88 for more info),. 2007 Pearson Education Australia,Constant returns to scale,A situation in which the long-run average cost curve does not change as the

28、 firm increases output.,. 2007 Pearson Education Australia,Diseconomies of scale,A situation in which the long-run average cost curve rises as the firm increases output Sources of diseconomies of scale: Bureaucracy Barriers to communication Management difficulties (e.g. lack of coordination). Produc

29、tion-line processes and interdependencies,. 2007 Pearson Education Australia,Long-run Costs,“To Scale” means that all inputs increase by the same proportion Decreasing returns to scale are quite different from diminishing marginal returns (where only the variable factor increases) DMR (short-run) an

30、d DRS (long-run),Profit Maximisation Sloman Ch 5,BUECO1507,Revenue,Defining total, average and marginal revenue total revenue: TR = P Q average revenue: AR = TR / Q marginal revenue: MR = TR / Q,Revenue,Revenue curves when price is not affected by the firms output (horizontal demand curve) average r

31、evenue (AR) marginal revenue (MR),Examining revenue curves in 2 situations,1) If a firm is very small relative to the whole market. 2) If a firm has a relatively large share of the market,O,O,AR, MR ($),Pe,S,D,D = AR = MR,Q (millions),Q (hundreds),(a) The market,The firm Being so small, its output,

32、whatever it is, does not affect market price at all,Average Revenue and Marginal Revenue curves(1) of a firm that is very SMALL relative to the whole market. (Price-taking firm),Price ($),TR,Quantity (units),0 200 400 600 800 1000 1200,Price = AR = MR ($),5 5 5 5 5 5 5,TR ($),0 1000 2000 3000 4000 5

33、000 6000,Total Revenue curve (1) of a firm that is very SMALL relative to the whole market. (Price-taking firm),Q,TR ($),Q (units),1 2 3 4 5 6 7,P =AR ($),8 7 6 5 4 3 2,TR ($),8 14 18 20 20 18 14,MR ($),6 4 2 0 -2 -4,MR,AR, MR ($),Quantity,AR,Average Revenue and Marginal Revenue curves(2) of a firm

34、that has a relatively LARGE share of the whole market.,If such a firm wants to sell more, it can only do so by lowering price. If it chooses to raise its price, it will have to accept lower sales. Therefore AR (price) slopes downward. How about the MR curve?,Q (units),1 2 3 4 5 6 7,P =AR ($),8 7 6 5

35、 4 3 2,TR ($),8 14 18 20 20 18 14,MR ($),6 4 2 0 -2 -4,MR,AR, MR ($),Quantity,AR,Average Revenue and Marginal Revenue curves(2) of a firm that has a relatively LARGE share of the whole market.,Supposing firm is selling 2 units at $7 each. It can sell the 3rd unit only by reducing the price of all un

36、its to $6. Selling the 3rd unit gains $6 but reducing the price of units 1 & 2 loses $1x2=$2. MR therefore = $6-$2=$4,TR,TR ($),Quantity (units),1 2 3 4 5 6 7,P = AR ($),8 7 6 5 4 3 2,TR ($),8 14 18 20 20 18 14,Total Revenue curve(2) of a firm that has a relatively LARGE share of the whole market.,Q

37、uantity,Revenue curves and price elasticity of demand,AR, MR ($),Quantity,MR,AR,Revenue curves and price elasticity of demand,Recall: a) When demand is elastic and price is reduced, total revenue increases. Total revenue increasing means MR is positive b) When demand is inelastic and price is reduce

38、, total revenue decreases. Total revenue decreasing means MR is negative,TR,Elastic,Inelastic,TR ($),TR Curve for a Firm Facing a Downward-sloping Demand Curve,Quantity,Revenue,Revenue curves when price varies with output (downward-sloping demand curve) average revenue (AR) marginal revenue (MR) tot

39、al revenue (TR) revenue curves and price elasticity of demand Shifts in revenue curves,Hidden,Determining a)Output where profit is maximisedb) Profit at that output,1) Using total curves maximising the difference between TR and TC 2) Using marginal and average curves,TR, TC, TP ($),TP,TR,TC,Quantity

40、,1) Using total curves,a) Profit is maximized when output is 3 b) Maximum profit is d-e,Quantity,Costs and revenue ($),MR,MC,2a) Using marginal and average curvesto determine profit maximising output,a) Profit is maximized at output of 3 Below 3 units, the firm should increase output because there will be a bigger addition to reven