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Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

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Page 1: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Lecture 2

Topics for today

• Possible problems in Quantitative Analysis Approach

• Variables and their types

• Some basic concepts relating probability

• Derivatives

Page 2: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Possible Problems in the Quantitative Analysis Approach

Problems are not easily identified

Conflicting viewpoints-linear or non linear relationship

Beginning assumptions

Fitting the textbook models

Validity of data

Hard-to-understand mathematics and statistics

Page 3: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Variables and their Types

Ratio scale Two values of a variable say X1 and X2,

(i)X1/X2 (ii)(X1-X2) (iii) X1≤ X2 and vice versa are meaningful quantities. Most economic

variable are ratio scale.

Interval Scale

Satisfies last two properties. Distance b/w two time periods (2012-1990) is meaningful.

But 1990/2012 is senseless.

Ordinal Scale

Only it satisfies the third property of ratio scale. Grades, A,B,C,D. Upper, Middle, Lower.

Example: Indifference curve in Economics

Nominal Scale:

None of the feature of ratio scale. Gender, male, female, marital status, single, married,

divorced, unmarried simply denote categories

Page 4: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives
Page 5: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Probability

• A probability is a numerical statement about the chance that an event will occur.

• Two basic rules regarding the probability

• 1- The probability, p, of any event is greater than or equal to 0 and less than or

equal to 1. 0≤p≤1

A- 0 means that an event is never expected to occur

b- 1 means that an event is always to occur.

2- The sum of the simple probabilities for all possible outcomes of an activity must be

equal to 1.

Examples:

Quantity Demanded Number of days

0 40 p=40/200 (.20)

1 80 p=80/200 (.40)

2 50 p=(50/200) (.25)

3 20

4 10

Page 6: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives
Page 7: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Types of probability

Two different ways to determine the probability

• Objective p(event)= number of occurrence of the event /total number of events

• Examples: tossing of a fair coin- it is based on the previous logic.

• Subjective: logic and history are not appropriate. So subjectivity arises.

Examples

• What is the probability that floods will come?

• What is the probability that depression will come in an economy?

• Which party will win the coming election in Pakistan?

• For this opinion polls are conducted and then probabilities are found.

Page 8: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Mutually exclusive and collectively exhaustive events

Mutually exclusive events : If only one of the event can occur on any one trial.

Collectively exhaustive events: They are said to be mutually exhaustive if the list include all the possible outcomes i.e. A U B= S.

Not mutually exclusive

The occurrence of one event does not restrict the occurrence of the other event.

• Examples: Drawing a 5 and drawing a diamond from a deck of cards- it can be both

5 and diamond

Page 9: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Adding mutually exclusive events• We are interested in whether one event or second event will occur.

• When events are mutually exclusive the law of addition is simply as follows.

• P(event A or event B)= p(event A)+ p(event B)

• Drawing spade or drawing a club out of a deck card are mutually exclusive.

13/52+13/52=1/2

• Venn diagram

• Addition of not mutually exclusive events.

• P(A or B)= P(A)+P(B)-P(A and B)

• Venn diagram

• Examples:

• In a math class of 30 students, 17 are boys and 13 are girls. On a unit test, 4 boys and 5

girls made an A grade. If a student is chosen at random from the class, what is the

probability of choosing a girl or a student with A Grade?

• P(girl or A)= P(girl)+ P(A)- P(girl and A)= 13/30+9/30-5/30=17/30

Page 10: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives
Page 11: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Some Basic Concepts in Mathematics

Derivatives • Definition

• Maxima

• Minima

Rules of Derivatives

1- Constant function rule

2- Power function rule

3- Sum difference rule

4- Product rule

5- Quotient rule

6- Chain rule

7- Inverse function rule

8- Partial Derivatives

Page 12: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives
Page 13: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Notation

Dependent variable Independent variable

Explained variable Explanatory variable

Predictand Predictor

Regressand Regressor

Response Stimulus

Endogenous Exogenous

Outcome Covariate

Controlled variable Control variable

LHS RHS

Page 14: Lecture 2 Topics for today Possible problems in Quantitative Analysis Approach Variables and their types Some basic concepts relating probability Derivatives

Summary

• Quantitative techniques not free from problems

• Probability

• Variables and their types

• Derivative