College Board - “Acorn Book” Course Description6-8%

II. Research Methods

Scientific Bases of Psychology

Unit II. Methods3

Summary Outline

Unit II. Methods4

A. Experimental, Correlational, and Clinical Research

1. Correlational (e.g. observational, survey, clinical

2. Experimental B. Statistics

1. Descriptive 2. Inferential

C. Ethics in Research

A. Experimental, Correlational, and Clinical Research

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Testable Hypotheses Operational Definitions Correlational Relationships

“Correlation does not imply causation”

Causal Relationships

A.1. Correlational (e.g. observational, survey,

clinical

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Naturalistic ObservationCase StudiesSurveys Correlational Research

Natural Observation

Professor Wainwright’s painstaking field research to decode the language of bears comes to a sudden and horrific end

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Natural ObservationNaturalistic Observation Exercise

by Alan FeldmanStudents work in teams to observe in public

placesThey observe alone, write up observations,

and compare observations later

Natural Observation in the Real Worldby Marissa M. SarabandoStudents work in teams to observe in public

placesThey are asked to make a hypothesis of what

they expect to observe Share the results in classHypothesis supported or not?

Insight into Negative Correlation

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Experimental & Control Groups

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A.2. Experiments

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Experimental DesignSelection of Participants

PopulationSampleRandom sampling

Assignment of Participants to GroupsExperimental GroupControl GroupRandom Assignment

Key Ideas in Experiment Design

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Treatment of GroupsVariables

Independent Variable (IV) Dependent Variable (DV)

PlaceboExperimenter Bias (double-blind

design)

Identifying Independent Variables and Dependent Variables

Martin Anderson

For the following statements create an hypothesis (Your hypothesis should, theoretically, be testable). Then identify the IV and DV.

Blondes have more fun.Hypothesis: Changing people’s hair color to blonde will

increase the amount of fun that they have.IV ____________________ DV __________________

A rolling stone gathers no moss.Hypothesis: IV ____________________ DV __________________

A researcher is interested in how the activity level of 4-year-olds is affected by viewing Teenage Mutant Ninja Turtles. He shows one group a 30-minute video of Teenage Mutant Ninja Turtles and another group a 30-minute video of Barney.

IV:______________DV:_______________Experimental group:__________________Control group:_______________________

An Exercise in Designing Research

Turn the saying “An apple a day keeps the doctor away” into a hypothesis and design an experiment to test its validity. (This chart can be used to analyze other experiments)

Other Ideas for Research Design

An Exercise in Designing Research Step One: Form an hypothesis

Form an Hypothesis

Hypothesis

State the relationship you expect to find.

The hypothesis needs to be testable. Think in terms of operational definitions.

An Exercise in Designing ResearchStep Two: Pick your subjects

Pick Subjects Subject Selection

Describe the process you will use to select subjects for your experiment.

The population is the group you are studying, Your subjects are a sample from the population.

An Exercise in Designing Research Step Three: Assign your subjects to groups

Assign Subjects

Assignment to Group

Describe how you will divide the subjects into the control group and the experimental group.

The control group and experimental group should be as similar as possible to each other.

An Exercise in Designing Research Step Four: Defining your independent variable

Independent Variable

Experimental Group

Control Group

Describe your Operational Definition - How are you going to measure the IV?

This group “gets” the IV.

This group doesn’t “get” the IV. (It might get a placebo, however).

An Exercise in Designing Research Step Five: Defining your dependent variable

Dependent Variable

Expected Result

Expected Result

Describe your Operational Definition – How are you going to measure the DV?

The DV is the same for both groups.

You expect a measurable difference between the groups.

An Exercise in Designing Research Step Six: Statistical analysis

Analysis of Outcomes Comparison of Groups

How are you going to see if the groups are different?(You do not need to identify the exact statistical procedures)

The statistical analysis gives you an idea if the differences between the two groups are big enough to be greater than chance.

Experimenter Bias

The experimenter may consciously or unconsciously

do things that can affectthe experiment so that it will confirm the experimenter’s

hypothesis.

Possible sources of

Experimenter Bias

 

Ways to control for

Experimenter Bias.

Confounding Variables Variables (other than the variables that are being

studied)that can have an affect on the outcome of the study.

Possible Confounding Variables

Ways to control for Confounding

Variables

Explain Blind and Double Blind

Designs

Confounding Variable

“When Dr. Henderson comes in, everybody play dead.”

Ethical Considerations

Basic Ethical Principles

•Informed Consent (Use of Deception?)

•Protection from harm and discomfort

•Confidentiality of information about participants

•Debriefing participants after the research

Describe how ethical considerations will be

dealt with in the research.

Flawed Experiment(Source unknown) A psychologist wishes to study the effect of a

reinforcement of food on the performance of a fine motor skill involving eye hand coordination. To accomplish this, he had his subjects thread as many needles as possible in a five minute period.

The subjects were divided into two groups: Males Females TotalGroup A 20 30 50Group B 28 22 50

The psychologist explained the tests to each group in the same way. However, she offered Group A a voucher for a free lunch for every 20 needles threaded. After the five-minute time period had expired, he counted the number of needles threaded by each group.

Flawed Experiment The results were as follows:

Total Number of Needles Average Number of Needles Threaded Threaded per Person Group A 80 1.8 Group B 45 0.9

From these results, the psychologist concluded that the reward of food caused Group A to thread more needles that Group B.

What was the independent variable? What was the dependent variable?

Which of the two groups was the control group? Why? Which of the two groups was the experimental group?

Why? How could the following variables negate the psychologist’s

conclusions? Age of the subjects? Sex of the subjects?

B.1. Descriptive Statistics

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Measures of Central TendencyModeMedianMean

Measures of VariabilityRangeStandard Deviation

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Normal Curve - Normal Distribution68%

Skew – Skewed DistributionsPositive SkewNegative Skew

Creating A Living Frequency Distribution:A Way to Introduce Key Statistical Terms and ConceptsMartin Anderson

Overview This exercise demonstrates basic statistical concepts.

By forming a “living frequency distribution” based on height, students will gain direct, first-hand knowledge of the following terms and the concepts they represent:

Variable Discrete, Continuous

Nominal Classification Dichotomy / Trichotomy

Continuum Measures of Central Tendency

Median, Mode, Arithmetic Mean Measures of Variability

Range Distribution

Histogram, Normal Curve, Skew, Outlier

Creating A Living Frequency Distribution (2)

MaterialsCardboard sheets for signsMarking pen30’ length of cord (extension cords connected together

work well)Create signs labeled with key terms and

concepts as follows to give to designated students:Median, Mode (best to make several of these), Range

From , Range ToCreate additional signs to indicate various

heights from 4’6” through 6’5”: Time Required

This exercise is easily done in one class period.

Creating A Living Frequency Distribution (3)

Step One: Creating a DichotomyI ask students to divide into two groups - tall

individuals on one side of the room and short individuals on the other

Step Two: Creating a Continuum

Step Three: Identifying the Median

Step Four: Identifying the Range

Creating A Living Frequency Distribution (4)

Step Five: Identifying the Mode Step Five: Calculating Arithmetic MeanStep Six: Demonstrating Normal

Distribution

Creating A Living Frequency Distribution (5)

Step Seven: Demonstrating SkewStep Seven: DiscussionStep Eight: Follow-up

A Three-Dimensional Model of the Normal CurveWilliam E. Addison & Kristine R. Hillman A common problem is conceptualizing

relationships among areas under the normal curve

Students have access to a wooden model of the normal curve.

The model consists of a total of six pieces, two each of three different sections.2 of 34%, 2 of 14%, 2 of 2%

The pieces correspond in relative size and shape to approximate areas delineated by standard deviation units in an empirical normal distribution This helps them to visualize the concept of

symmetry And how the symmetry of the normal curve relates

to concepts such as central tendency, variability, relative standing

Normal Distribution Curve

Insight into Negative Correlation

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Correlation CoefficientsPositive CorrelationNegative Correlation

Discussion: Ways to explain and demonstrate this to students.

2. Inferential

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Evaluation of chance Probability that results are by chance alone

Tests of SignificanceDetermine the likelihood that a specific outcome was obtained by chance alone

Importance of Random Assignment

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Is it Representative? Can we Generalize? Sample / PopulationReplication

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What is “Significance?”Common Usage

ImportantMeaningfuletc.

Term of Art: Statistical Significance ReliableRepeatable

Significance TestingSignificant Result in Research

Not necessarily large or importantNot necessarily dramaticBut probably did not occur by chance

Null HypothesisOpposite of Hypothesis

Hypothesis: Anxiety reduces test performance

Null Hypothesis: Anxiety does not effect test performance.

Significance Testing (continued)

p-level (Probability Level)Probability that your null hypothesis is

correctProbability that the statistic is really zero

Examples:Difference in meansCorrelation coefficient

p < .05 (p < .01)Your null hypothesis has less than a 5%

chance of being rightYou have less than a 5% chance of being

wrong

Type I and Type II Errors

Type I ErrorDeciding that one variable has an effect on (or

a relationship to) another variable when it doesn’t

p-level gives the odds of making this kind of error

Type II ErrorDeciding that one variable does not have an

effect on (or a relationship to) another variable when it does

There is no easy way to estimate the odds of this kind of error

C. Ethics in Research

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Informed consentMinimize risk and discomfort

Potential benefits must outweigh risk to subjects

Confidentiality DebriefingEthics of animal researchApproval of research committee

How Psychologists Do Research

Spearman Rank Order Correlation Coefficient

We have seven subjects whose art projects are being ranked by two judges, and we wish to know if the two judges rankings are related to one another. In other words, do the two judges tend to rank the seven art show contestants in the same way?

The formula for the Spearman Correlation Coefficient is:

In which

r2 = Spearman

Correlation Coefficient

∑ = Sum of

D2 = Difference squared

N = number of subjects

Spearman Rho for Rankings of Two Judges of Art Projects for Seven Subjects

subject Judge A

Ranking

Judge B

Ranking D D2

Alan 1 2 -1 1

Betty 2 1 1 1

Carlos 3 4 -1 1

Diana 4 3 1 1

Edward 5 6 -1 1

Fern 6 7 -1 1

Greg 7 5 2 4

∑ 10

Thus we can see that there is a high positive correlation, but not a perfect correlation between the two judges ratings.