2 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 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 CHAPTER OVERVIEW From Problem to Solution All About Variables Other Important Types of VariablesHypothesesSamples and PopulationsThe Concept of Significance
13 THE RELATIONSHIP BETWEEN INDEPENDENT AND DEPENDENT VARIABLES: THE RELATIONSHIP BETWEEN INDEPENDENT AND DEPENDENT VARIABLES: WHAT MAKES GOOD VARIABLES?Independent variable is not confoundedLevels do not vary systematically with other variablesDependent variable is sensitive to changes in the independent variable
15 OTHER IMPORTANT TYPES OF VARIABLES Control Variable: Has a potential influence on the dependent variableExtraneous Variable: Has an unpredictable impact on the dependent variableModerator Variable: Variables related to independent or dependent variables, and hiding the true relationship between independent and dependent variables
16 Other Terms You Might See VARIABLES—A SUMMARYType of VariableDefinitionOther Terms You Might SeeDependentA variable that is measured to see whether the treatment or manipulation of the independent variable had an effectOutcome variableResults variableCriterion variableIndependentA variable that is manipulated to examine its impact on a dependent variableTreatmentFactorPredictor variableControlA variable that is related to the dependent variable, the influence of which needs to be removedRestricting variableExtraneousA variable that is related to the dependent variable or independent variable that is not part of the experimentThreatening variableModeratorA variable that is related to the dependent variable or independent variable and has an impact on the dependent variableInteracting variable
18 HYPOTHESIS Reflects the general problem under study Restates the general problem in a form that is precise enough to allow testing
19 NULL HYPOTHESISStates that there is no relationship between the independent and dependent variables under studyHo: µ1 = µ2Ho: Null hypothesisµ1: Theoretical average of population 1µ2: Theoretical average of population 2
20 PURPOSE OF NULL HYPOTHESIS A starting point for analysisAccepted as true absent other informationAssumes that chance caused any observed differencesProvides a benchmark for comparison
21 THE RESEARCH HYPOTHESIS A statement of inequalityA relationship exists between the independent and dependent variablesH1: ≠H1: Research hypothesis: Theoretical average of population 1: Theoretical average of population 2X1X2
22 DIRECTIONAL VS. NONDIRECTIONAL RESEARCH HYPOTHESES Nondirectional Research HypothesisGroups are different, but direction is not specifiedH1: ≠Directional Research HypothesisGroups are different, and direction is specifiedH1: >H1: <X1X2X1X2X1X2
23 PURPOSE OF RESEARCH HYPOTHESIS Directly tested during research processTo compare against null hypothesis
24 DIFFERENCES BETWEEN NULL AND RESEARCH HYPOTHESES Equality between variablesRefers to populationIndirectly testedStated using Greek symbols (µ)ImpliedResearchInequality between variablesRefers to sampleDirectly testedStated using Roman symbols ( )ExplicitX
25 WHAT MAKES A GOOD HYPOTHESIS? Is stated in declarative formPosits a relationship between variablesReflects theory or literatureIs brief and to the pointIs testable
29 SIGNIFICANCEObserved differences (PROBABLY) result from the treatment and not from chanceWhy?Influences other than the treatmentSignificance level = risk associated with not being 100% certain that null hypothesis is incorrect
30 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 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?