1. © 2009 Pearson Prentice Hall, Salkind. Chapter 2 The Research Process: Coming to Terms

2. © 2009 Pearson Prentice Hall, Salkind. CHAPTER OBJECTIVES - STUDENTS SHOULD BE ABLE TO: Describe the research process from formulating questions to seeking and finding solutions. Describe the difference between dependent and independent variables. Identify other types of variables that may interfere with the research process. Define a hypothesis and describe how it works. Discuss the value of the null hypothesis.

3. © 2009 Pearson Prentice Hall, Salkind. OBJECTIVES, CONTINUED - STUDENTS SHOULD BE ABLE TO: Describe the differences between a null hypothesis and a research hypothesis. List the characteristics of a good hypothesis. Explain the difference between a sample and the population. Define statistical significance and explain its importance.

4. © 2009 Pearson Prentice Hall, Salkind. CHAPTER OVERVIEW From Problem to Solution All About Variables Other Important Types of Variables Hypotheses Samples and Populations The Concept of Significance

5. © 2009 Pearson Prentice Hall, Salkind. FROM PROBLEM TO SOLUTION

6. © 2009 Pearson Prentice Hall, Salkind. WHAT IS RESEARCH ALL ABOUT, ANYWAY? Increasing our understanding of how and why we behave the way we do!!

7. © 2009 Pearson Prentice Hall, Salkind. 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

8. © 2009 Pearson Prentice Hall, Salkind. ALL ABOUT VARIABLES

9. © 2009 Pearson Prentice Hall, Salkind. VARIABLES Variables are 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

10. © 2009 Pearson Prentice Hall, Salkind. DEPENDENT VARIABLES The outcomes of a research study Depend on the experimental treatment

11. © 2009 Pearson Prentice Hall, Salkind. INDEPENDENT VARIABLES Treatments or conditions under control of the researcher Levels—at least two different values of the independent variable must be present

12. © 2009 Pearson Prentice Hall, Salkind. INDEPENDENT VARIABLES IN FACTORIAL DESIGNS

13. © 2009 Pearson Prentice Hall, Salkind. THE RELATIONSHIP BETWEEN 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 independent variable

14. © 2009 Pearson Prentice Hall, Salkind. OTHER IMPORTANT TYPES OF VARIABLES

15. © 2009 Pearson Prentice Hall, Salkind. OTHER IMPORTANT TYPES OF VARIABLES Control Variable: Has a potential influence on the dependent variable Extraneous Variable: Has an unpredictable impact on the dependent variable Moderator Variable: Variables related to independent or dependent variables, and hiding the true relationship between independent and dependent variables

16. © 2009 Pearson Prentice Hall, Salkind. VARIABLES—A SUMMARY Type of Variable DefinitionOther Terms You Might See Dependent A variable that is measured to see whether the treatment or manipulation of the independent variable had an effect Outcome variable Results variable Criterion variable Independent A variable that is manipulated to examine its impact on a dependent variable Treatment Factor Predictor variable Control A variable that is related to the dependent variable, the influence of which needs to be removed Restricting variable Extraneous A variable that is related to the dependent variable or independent variable that is not part of the experiment Threatening variable Moderator A variable that is related to the dependent variable or independent variable and has an impact on the dependent variable Interacting variable

17. © 2009 Pearson Prentice Hall, Salkind. HYPOTHESES

18. © 2009 Pearson Prentice Hall, Salkind. HYPOTHESIS Reflects the general problem under study Restates the general problem in a form that is precise enough to allow testing

19. © 2009 Pearson Prentice Hall, Salkind. NULL HYPOTHESIS States that there is no relationship between the independent and dependent variables under study H o : µ 1 = µ 2  H o : Null hypothesis  µ 1 : Theoretical average of population 1  µ 2 : Theoretical average of population 2

20. © 2009 Pearson Prentice Hall, Salkind. 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

21. © 2009 Pearson Prentice Hall, Salkind. THE RESEARCH HYPOTHESIS A statement of inequality A relationship exists between the independent and dependent variables H 1 : ≠ –H 1 : Research hypothesis – : Theoretical average of population 1 – : Theoretical average of population 2 X1X1 X2X2 X1X1 X2X2

22. © 2009 Pearson Prentice Hall, Salkind. DIRECTIONAL VS. NONDIRECTIONAL RESEARCH HYPOTHESES Nondirectional Research Hypothesis  Groups are different, but direction is not specified  H 1 : ≠ Directional Research Hypothesis  Groups are different, and direction is specified  H 1 : >  H 1 : < X1X1 X1X1 X2X2 X1X1 X2X2 X2X2

23. © 2009 Pearson Prentice Hall, Salkind. PURPOSE OF RESEARCH HYPOTHESIS Directly tested during research process To compare against null hypothesis

24. © 2009 Pearson Prentice Hall, Salkind. Research  Inequality between variables  Refers to sample  Directly tested  Stated using Roman symbols ( )  Explicit DIFFERENCES BETWEEN NULL AND RESEARCH HYPOTHESES Null  Equality between variables  Refers to population  Indirectly tested  Stated using Greek symbols (µ)  Implied X

25. © 2009 Pearson Prentice Hall, Salkind. WHAT MAKES A GOOD HYPOTHESIS? Is stated in declarative form Posits a relationship between variables Reflects theory or literature Is brief and to the point Is testable

26. © 2009 Pearson Prentice Hall, Salkind. SAMPLES AND POPULATIONS

27. © 2009 Pearson Prentice Hall, Salkind. 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

28. © 2009 Pearson Prentice Hall, Salkind. SIGNIFICANCE

29. © 2009 Pearson Prentice Hall, Salkind. 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

30. © 2009 Pearson Prentice Hall, Salkind. HAVE WE MET THE OBJECTIVES? CAN YOU: Describe the research process from formulating questions to seeking and finding solutions? Describe the difference between dependent and independent variables? Identify other types of variables that may interfere with the research process? Define a hypothesis and describe how it works? Discuss the value of the null hypothesis?

31. © 2009 Pearson Prentice Hall, Salkind. OBJECTIVES, CONTINUED CAN YOU: Describe the differences between a null hypothesis and a research hypothesis? List the characteristics of a good hypothesis? Explain the difference between a sample and the population? Define statistical significance and explain its importance?