S519: Evaluation of Information Systems

Social Statistics

Ch6: Hypothesis

This week

The difference between a sample and a population

Null and research hypotheses What is a good hypothesis

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

Research and reality

$$$ Time

Sampling: Sample vs. population Sampling errors measure how well a sample

approximates the characteristics of a population.

Sampling

A representative sample Represent population as close as it can Ensuring the high similarity of both Time and $$$

The Steps of Hypothesis Testing

1. State the hypothesis

2. Set decision criteria

3. Collect data and compute sample statistic

4. Make a decision (accept/reject)

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.

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 factors.

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.

Nondirectional research hypothesis

Reflects the difference between groups, but the direction of the difference is not specified (such as more than or less than)

YXH :

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

ExercisesNull hypothesis Nondirectional

research hypothesisDirectional research hypothesis

There is no difference between the score of the test and the time spending for assignments in the class.

There is no difference between the consumption of ices cream and crime

There is no difference between reading more papers and writing good paper

There is no differences for the kid’s reading behavior and kid’s eating habit

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.

Exercises

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