S519: Evaluation of Information Systems

1. S519: Evaluation of Information Systems Social Statistics Ch6: Hypothesis

2. Last week

3. This week • The difference between a sample and a population • Null and research hypotheses • What is a good hypothesis

4. What is a hypothesis? • Hypothesis • An educated guess • Research questions  hypothesis • A good hypothesis translates a problem or research question into a form that is more amendable to testing • Practical way: test your hypothesis in a sample and generalize it to the larger population

5. Research and reality • $$$ • Time • Sampling: • Sample vs. population • Sampling errors measure how well a sample approximates the characteristics of a population.

6. Sampling • A representative sample • Represent population as close as it can • Ensuring the high similarity of both • Time and $$$ • What is a big sample?

7. Null hypothesis • Assumes no relationship between two variables that you are going to study • Such as there will be no difference in the average score of 9th graders and the average score of 12th graders on the ABC memory test. • There is no difference between white and black families in the amount of assistance offered to their children in school-related activities.

8. Null hypothesis • A starting point • In the absence of any other information,  guess? • Benchmark against other outcomes • To compare with other observed outcomes to see if these differences are due to some other factor

9. Research hypothesis • A definite statement that there is a relationship between variables • Null hypothesis  research hypothesis • There is no difference between white and black families in the amount of assistance offered to their children in school-related activities. • There is a difference between white and black families in the amount of assistance offered to their children in school-related activities.

10. Nondirectional research hypothesis • Reflects the difference between groups, but the direction of the difference is not specified (such as more than or less than)

11. Directional research hypothesis • Reflects the difference between groups, and the direction of the difference is specified. • The average score of 12th graders is greater than the average score of 9th graders on the ABC memory test. • Either • H: X > Y or H: X < Y

12. Exercises

13. Null vs. research hypothesis • Differences? • No relationship vs. has relationship • Refer to population vs. refer to sample • Indirectly tested vs. directly tested • Greek symbols vs. roman symbols

14. Good hypothesis • Criteria • Stated in a declarative form and not as a question • Posits an expected relationship between variables • Reflects theory or literature • Be brief and to the point • Testable and measureable • Parents who enroll their children in after-school programs will miss fewer days of work in one year and will have a more positive attitude toward work than will parents who do not enroll their children in such programs.

15. Exercises Lab • Take three empirical research articles, find • What is the null hypothesis • What is the research hypothesis • Create your own null and research hypothesis in your interested area. • Evaluate your hypothesis based on the criteria, • What are hypothesis for your group project