Week Three Assignment: Descriptive Statistics & Data Displays

Chapter7.pdf

Chapter 7    Hypotheticals and You: Testing Your Questions

What You Will Learn in Chapter 7  Understanding the difference between a

sample and a population

 Understanding the importance of the null and research hypotheses

 Using criteria to judge a good hypothesis

What Is a Hypothesis?  An “educated guess”

 Its role is to reflect the general problem statement or question that is driving the research.

 Translates the problem or research question into a form that can be tested

Samples and Populations  Population: The large group to which you

would like to generalize your findings

 Sample: The smaller, representative group of the population that is used to do the research

 Sampling error: A measure of how well a sample represents the population

Hypotheses  Two major types  Research hypotheses  Null hypotheses

 Null hypotheses refer to populations and are written in Greek symbols

 Research hypotheses refer to samples and are written in Roman symbols

The Null Hypothesis  Statements that contain two or more things

that are equal (unrelated) to one another

H0 : µ1 = µ2

 The starting point—it is accepted as true without knowing more information

 Benchmark to compare actual outcomes

The Research Hypothesis  Statement that there is a relationship

between two variables

 Statements of inequality

 There are two types of research hypotheses

 Directional

 Nondirectional

Nondirectional Research Hypotheses

 Reflect a difference, but the direction is not specified

 Use a two-tailed test

Nondirectional Research Hypothesis Example

 H1 : X1 ≠ X2

Directional Research Hypotheses

 Reflect a difference, and the direction is specified

 Use the one-tailed test

Differences Between Null and Research Hypotheses

What Makes a Good Hypothesis? In sum, good hypotheses should  be stated in declarative form,

 posit a relationship between variables,

 reflect a theory or a body of literature on which they are based,

 be brief and to the point, and

 be testable.