Unit 2 (C):Unit 2 (C):Experimental Experimental

Research DesignsResearch Designs

Mr. McCormickMr. McCormickA.P. PsychologyA.P. Psychology

Do-NowDo-Now(Discussion)(Discussion)

What is a What is a correlationcorrelation??

What is a What is a positive correlationpositive correlation?? What is the What is the correlation coefficient (r)correlation coefficient (r)

for a for a perfect positive correlationperfect positive correlation?? What does a positive correlation What does a positive correlation looklook

like?like? Provide an Provide an exampleexample of two things that of two things that

may be may be positivelypositively correlated. correlated.

What is a What is a negative correlationnegative correlation?? What is the What is the correlation coefficient (r) correlation coefficient (r)

for a for a perfect negative correlationperfect negative correlation?? What does a negative correlation What does a negative correlation looklook

like?like? Provide an Provide an example example of two things that of two things that

may be may be negativelynegatively correlated correlated..

Non-ExperimentalNon-ExperimentalResearch DesignsResearch Designs

Activity:Activity: With a partner, create an With a partner, create an exampleexample of a psychological of a psychological

phenomenon a psychologist would likely study for any phenomenon a psychologist would likely study for any 22 of of the following the following non-experimental research designsnon-experimental research designs. . Explain Explain whywhy..

Naturalistic ObservationNaturalistic Observation Case StudyCase Study SurveySurvey Longitudinal StudyLongitudinal Study Cross-Sectional StudyCross-Sectional Study CorrelationCorrelation

For each example, provide a short For each example, provide a short explanationexplanation of why each of why each research design would be most research design would be most preferablepreferable for that scenario for that scenario

Experimental Research Experimental Research DesignsDesigns

Experiment:Experiment: A research method in which an A research method in which an

investigator investigator manipulatesmanipulates one or more one or more variables variables (independent variables) (independent variables) to to observe the observe the effecteffect on some behavior or on some behavior or mental process mental process (dependent variable)(dependent variable)

Experimental Research Experimental Research DesignsDesigns

Why might psychological Why might psychological researchers researchers prefer prefer experimental experimental research designs research designs over over descriptive or descriptive or correlational correlational research designsresearch designs??

What type of What type of researchresearch might might require an require an experimental designexperimental design??

Experimental Research Experimental Research DesignsDesigns

Experiments begin with a hypothesis Experiments begin with a hypothesis (e.g. “Caffeine improves test (e.g. “Caffeine improves test

performance”)performance”)

Experimental Research Experimental Research DesignsDesigns

Experimenters must employ variables:Experimenters must employ variables: Independent Variable:Independent Variable:

Manipulated/changed by experimenter to observe Manipulated/changed by experimenter to observe its effects (e.g. Coffee/Redbull)its effects (e.g. Coffee/Redbull)

Dependent Variable:Dependent Variable: The effects/changes that occur in relation to the The effects/changes that occur in relation to the

independent variable (e.g. improved test independent variable (e.g. improved test performance)performance)

Confounding Variables:Confounding Variables: Factors other than the independent variable that Factors other than the independent variable that

might produce an effect in an experiment (e.g. one’s might produce an effect in an experiment (e.g. one’s natural intelligence)natural intelligence)

Experimental Research Experimental Research DesignsDesigns

Experimenters divide participants Experimenters divide participants into two groups (often randomly):into two groups (often randomly): Experimental Group:Experimental Group:

Independent variable is applied (e.g. Coffee Independent variable is applied (e.g. Coffee is given to participants)is given to participants)

Control Group:Control Group: Treated the same way as experimental group, Treated the same way as experimental group,

but independent variable is not applied (e.g. but independent variable is not applied (e.g. No coffee is given to participants)No coffee is given to participants)

Experimental Research Experimental Research DesignsDesigns

Why would Why would experimentersexperimenters

wish to wish to employemploy an an experimentalexperimental and a and a

control groupcontrol group??

Experimental Research Experimental Research DesignsDesigns

Does Does breast-feedingbreast-feeding a child a child improveimprove their their intelligenceintelligence later in life?later in life?

ReviewReview A psychologist wishes to test the effects of cell A psychologist wishes to test the effects of cell

phone use on driving. To do so, he creates an phone use on driving. To do so, he creates an experiment in which 80 participants partake in a experiment in which 80 participants partake in a driving test. 40 participants must talk on their driving test. 40 participants must talk on their phone while driving, while 40 participants may not. phone while driving, while 40 participants may not. Identify the following: Identify the following:

HypothesisHypothesis Independent VariableIndependent Variable Dependent VariableDependent Variable Confounding VariablesConfounding Variables Experimental GroupExperimental Group Control GroupControl Group

HomeworkHomework

Unit 2 Quiz: Unit 2 Quiz: “Research Methods”“Research Methods”