Theories and models( 4) General features of economic model 3. Positive and normative distinction Positive analysis(实证分析) is the use of theories and models to explain how resources actually are allocated in an economy Try to answer: What is(是什么) For example: What will be the impact of an import quota (it 口配额) on foreign cars? Chapter 1
Chapter 1 25 Theories and Models （ 4 ） General Features of Economic Model: 3. Positive and Normative Distinction Positive Analysis(实证分析 ) is the use of theories and models to explain how resources actually are allocated in an economy Try to answer: What is（是什么） For example: What will be the impact of an import quota（进 口配额） on foreign cars?
Theories and Models (5) Positive and normative distinction Normative analysis(规范分析) is theories that make value judgments about how the economic resource should be allocated Try to answer:" What ought to be?”(应该 是什么) For example Whether should an import quota ( be used on foreign cars or not? Chapter 1 26
Chapter 1 26 Theories and Models （ 5 ） Positive and Normative Distinction Normative analysis（规范分析） is theories that make value judgments about how the economic resource should be allocated Try to answer: “What ought to be? ”（应该 是什么） For example: Whether should an import quota （be used on foreign cars or not?
The positive-normative Distinction Distinction between theories that seek to explain the world as it is and theories that postulate the way the world should be To many economists the correct role for theory is to explain the way the world is positive rather than the way it should be (normative) Positive economics is the primary approach of the text Chapter 1
Chapter 1 27 The Positive-Normative Distinction Distinction between theories that seek to explain the world as it is and theories that postulate the way the world should be To many economists, the correct role for theory is to explain the way the world is (positive) rather than the way it should be (normative) Positive economics is the primary approach of the text
How Economists Verify Theoretical models a Two methods are used Direct Approach(直接验证法) Testing Assumptions: Verifying economic models by examining validity of the assumptions on which they are based Indirect Approach(间接检验法) Testing Predictions: Verifying economic models by asking if they can accurately predict real-World events Chapter 1
Chapter 1 28 How Economists Verify Theoretical Models Two methods are used Direct Approach（直接验证法）: Testing Assumptions: Verifying economic models by examining validity of the assumptions on which they are based Indirect Approach (间接检验法) Testing Predictions: Verifying economic models by asking if they can accurately predict real-world events
Testing assumptions One approach would be to determine if the assumptions are reasonable The obvious problem is that people have differing opinion regarding reasonable Empirical evidence can also be used Results of such methods have had problems similar to those found in opinion polls Chapter 1
Chapter 1 29 Testing Assumptions One approach would be to determine if the assumptions are reasonable The obvious problem is that people have differing opinion regarding reasonable Empirical evidence can also be used Results of such methods have had problems similar to those found in opinion polls