1. Unit 3
Hypothesis

2. Meaning Tentative solutions proposed by the researcher
Intelligent and logical guesses about possible differences, relationships, causes and solutions
These may or may not be real solutions to the problem
Whether they are or not is to be tested by the researcher
A predictive statement , capable of being tested by scientific methods that relates an independent variable to dependent variable

3. Definition
A tentative generalization, the validity of which remains to be tested. In most elementary stage hypothesis may be any guess, hunch , imaginative idea which becomes the basis for action or investigation

4. Characteristics of Hypothesis
Clarity
Empirically testable
Specific
Simple to understand
Consistency
Time bound
Consider all aspects of a problem

5. Importance of Hypothesis
Provides definite focus
Spells out the difference between precision and haphazardness
Suggests the type of research
Suggests the type of analysis
Helps to develop theory

6. Types of Hypothesis Null and Alternative hypothesis Null Hypothesis
If we are to compare method A with method B about its superiority and if we proceed on the assumption that both methods are equally good, then this assumption is termed as Null hypothesis
Symbolized as Ho
Alternative Hypothesis
We may think that method A is superior and method B is inferior, then this assumption is Alternative hypothesis
Symbolized as Ha

7. Null and Alternative Hypothesis
Suppose we assume that the mean attendance of a class is 70.
Null hypothesis
H0 :µ= µ H0 =70 (Null hypothesis is that the mean attendance of a class is 70)
Alternative Hypothesis
Ha : µ≠ µ H0 (The alternative hypothesis is that mean attendance of class is not equal to 70. It may be more or less than 70)
Ha : µ> µ H0 (The alternative hypothesis is that mean attendance of class is greater than 70)
Ha : µ< µ H0 (The alternative hypothesis is that mean attendance of class is less than 70)

8. Null hypothesis and Alternative hyothesis
Alternative hypothesis is usually the one which one wishes to prove and null hypothesis is the one which one wishes to disprove
Null hypothesis represents the hypothesis we are trying to reject and alternative hypothesis represents all other possibilities

9. Level of Significance Usually taken as 5% or sometimes 1%
5% level of significance means
Ho will be rejected when the result has less than 5%(.05) probability of occurring if Ho is true
Researcher is willing to take as much as 5% risk of rejecting Ho when it happens to be true
Level of significance is the maximum level of the probability of rejecting null hypothesis when it is true.
Usually determined in advance

10. Decision Rule
Given a hypothesis Ho and an alternative hypothesis Ha, we make a rule called decision rule according to which we accept Ho or reject Ho
If Ho is that a student is punctual( he/she is never late for the class) and Ha is that the student is not punctual ( he/she is usually late for the class), then we must decide the number of times to be tested and the criterion for accepting or rejecting H0.
We might test in 20 classes and plan our decision saying that if the student is on time up to 18 times we accept Ho else reject Ho.

11. Type 1 and Type 2 Errors Type 1 Error Type 2 Error
Rejecting Ho when Ho is true
Denoted by α (alpha)
Also called level of significance of test
Type 2 Error
Accepting Ho when Ho is false
Denoted by β

12. Type 1 and Type 2 Errors

13. Two tailed and One tailed tests
A two tailed test rejects null hypothesis if sample mean is significantly higher or lower than the hypothesized mean
It is appropriate when null hypothesis is some specified value and alternative hypothesis is not equal to the null hypothesis value.
Symbolically, two tailed test is appropriate when
H0 :µ= µ H and Ha : µ≠ µ H0

14. Two tailed test

15. One tailed test
A one tailed test is appropriate if we are to test whether sample mean is either significantly higher or lower than the hypothesized mean
It is appropriate when null hypothesis is some specified value and alternative hypothesis is either greater than or less than the null hypothesis value
Symbolically, two tailed test is appropriate when
H0 :µ= µ H and Ha : µ> µ H0 (Right tailed test) OR
H0 :µ= µ H and Ha : µ< µ H0 (Left tailed test)

16. One tailed tests
Right tailed test
Left tailed test

17. Procedure for Hypothesis testing
Steps undertaken to make a choice between accepting or rejecting null hypothesis
Making a formal statement
Both null and alternative hypothesis clearly stated
Selecting a significance level
Generally 5% or 1%

18. Procedure for Hypothesis testing
Deciding the distribution to use
T-distribution or normal distribution
Compute statistics
Calculate probability that sample result would diverge as widely as it has from expectations
Compare probability with specified level of significance
If calculated probability < α in one tailed or α/2 in two tailed test, reject Ho
If calculated probability > α in one tailed or α/2 in two tailed test, accept Ho

19. Tests of Hypothesis Parametric tests Non parametric tests
Used with normal distribution
Z-test, t-test, chi-square test, f-test
Non parametric tests
Distribution free
Sign test , Fisher-Irwin test, Signed rank test, rank sum tests etc.
Correlation Analysis
Finding out if there is a relationship between two or more variables
Regression Analysis
To establish cause and effect relationship between two variables

20. Thank You