1. CHAPTER OVERVIEW • All About Variables • The Relationship Between Independent and Dependent Variables • Other Important Types of Variables • Hypotheses • Samples and Populations • The Concept of Significance

2. WHAT IS RESEARCH ALL ABOUT, ANYWAY? Increasing our understanding of how and why we behave the way we do!!

3. THE RESEARCH PROCESS: COMING TO TERMS • From Problem to Solution • Noting an interesting question • Stating the question in such a way that it can be answered • The Language of Research

4. VARIABLES • A class of outcomes that can take on more than one value • The more precisely a variable is measured, the more useful the measurement is

5. DEPENDENT VARIABLES (DVs) • The Outcomes of a Research Study • Depends on the experimental treatment

6. INDEPENDENT VARIABLES (IVs) • Treatments or conditions under control of the researcher • Levels—at least two different values of the IV must be present

7. INDEPENDENT VARIABLES IN FACTORIAL DESIGNS

8. THE RELATIONSHIP BETEWEEN INDEPENDENT AND DEPENDENT VARIABLES: WHAT MAKES GOOD VARIABLES? • Independent Variable is not confounded • Levels do not vary systematically with other variables • Dependent Variable is sensitive to changes in the IV

9. OTHER IMPORTANT TYPES OF VARIABLES • Control Variable—Has a potential influence on the DV • Extraneous Variable—Has an unpredictable impact on the DV • Moderator Variable—Variables related to IVs and/or DVs, and hiding the true relationship between IVs and DVs

10. VARIABLES—A SUMMARY

11. HYPOTHESIS • Reflects the general problem under study • Restates the general problem in a form that is precise enough to allow testing

12. NULL HYPOTHESIS • States that there is no relationship between the independent and dependent variables under study • Ho: µ1 = µ2 • Ho: Null hypothesis • µ1: Theoretical average of population 1 • µ2: Theoretical average of population 2

13. PURPOSE OF NULL HYPOTHESIS • A starting point for analysis • Accepted as true absent other information • Assumes that chance caused any observed differences • Provides a benchmark for comparison

14. H1: ≠ • H1: Research hypothesis • : Theoretical average of population 1 • : Theoretical average of population 2 X1 X2 X1 X2 THE RESEARCH HYPOTHESIS • A statement of inequality • A relationship exists between the independent and dependent variables

15. X1 X1 X2 X1 X2 X2 DIRECTIONAL VS. NONDIRECTIONAL RESEARCH HYPOTHESES • Nondirectional Research Hypothesis • Groups are different, but direction is not specified • H1: ≠ • Directional Research Hypothesis • Groups are different, and direction is specified • H1: > • H1: <

16. PURPOSE OF RESEARCH HYPOTHESIS • Directly tested during research process • To compare against Null hypothesis

17. Research Inequality between variables Refers to sample Directly tested Stated using Roman symbols ( ) Explicit Null Equality between variables Refers to population Indirectly tested Stated using Greek symbols (µ) Implied X DIFFERENCES BETWEEN NULL AND RESEARCH HYPOTHESES

18. WHAT MAKES A GOOD HYPOTHESIS? • Stated in declarative form • Posits a relationship between variables • Reflects theory or literature • Brief and to the point • Testable

19. SAMPLES AND POPULATIONS • The SAMPLE is a representative portion of a POPULATION • The POPULATION is the entire group of interest • Results from the SAMPLE should generalize to the POPULATION

20. SIGNIFICANCE • Observed differences (PROBABLY) result from the treatment and not from chance • Why? • Influences other than the treatment • Significance level = risk associated with not being 100% certain that Null hypothesis is incorrect