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Research Strategies: How Psychologists

Ask and Answer Questions

Module 3

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Research Strategies: How Psychologists Ask and Answer

QuestionsDescription The Case Study

The Survey

Naturalistic Observation

Correlation Correlation and Causation Illusory Correlation Perceiving Order in Random

Events

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Research Strategies: How Psychologists Ask and Answer

QuestionsExperimentation Exploring Cause and Effect

Evaluating Therapies

Independent and Dependent Variables

Statistical Reasoning Describing Data

Making Inferences

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Descriptive MethodsCase Study

A technique in which one person is studied in depth to reveal underlying behavioral principles.

Is language uniquely human?

Advantage: tremendous amount of detail.Disadvantage: cannot apply to others.

Famous case study: Phineas Gage

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Survey

A technique for ascertaining the self-reported attitudes, opinions or behaviors

of people usually by questioning a representative, random sample of people.

http://ww

w.lynnefeatherstone.org

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Survey

Wording can change the results of a survey.

Q: Should cigarette ads and pornography be allowed on television? (not allowed vs.

forbid)

Wording Effect

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Survey

A tendency to overestimate the extent to which others share our

beliefs and behaviors.

False Consensus Effect

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Survey

Random SamplingFrom a population, if each member has an

equal chance of inclusion into a

sample, we call that a random sample

(unbiased). The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.

Population – all the cases in a group

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Random Sampling from Population

POPULATION

SAMPLE

INFERENCE

LO 1.9 Case studies and surveys

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Descriptive Methods• Naturalistic observation – watching animals

or humans behave in their normal environment.

• Major Advantage:– Realistic picture of behavior.

• Disadvantages:– Observer effect - tendency of people or

animals to behave differently from normal when they know they are being observed.

• Participant observation - a naturalistic observation in which the observer becomes a participant in the group being observed (to reduce observer effect).

Naturalistic and laboratory settings

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Descriptive Methods• Laboratory observation – watching animals

or humans behave in a laboratory setting.• Advantages:

– Control over environment.– Allows use of specialized equipment.

• Disadvantage:– Artificial situation that may result in

artificial behavior.

• Descriptive methods lead to the formation of testable hypotheses.

Naturalistic and laboratory settings

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Correlation

When one trait or behavior accompanies another, we say the two correlate.

Correlation coefficient

Indicates directionof relationship

(positive or negative)

Indicates strengthof relationship(0.00 to 1.00)

r = 0.37+

Correlation Coefficient is a statistical measure of relationship

between two variables.

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Finding Relationships

• Correlation coefficient ranges from 0 to 1.00• Closer to 1.00, the stronger the relationship between

the variables.– No correlation = 0.0.– Perfect correlation = -1.00 OR +1.00.

• Positive correlation – variables are related in the same direction.– As one increases, the other increases; as one decreases, the

other decreases.• Negative correlation – variables are related in opposite

direction.– As one increases, the other decreases.

• CORRELATION DOES NOT PROVE CAUSATION!!!

Correlational technique

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Perfect positivecorrelation (+1.00)

Scatterplot is a graph comprised of points generated by values of two variables.

Scatterplots

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No relationship (0.00)Perfect negativecorrelation (-1.00)

Scatterplot on the left shows a negative correlation, and the one on the right shows no

relationship between the two variables.

Scatterplots

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DataData showing height and temperament in people.

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Scatterplot

Scatterplot showing relationship between height and temperament in people with a moderate positive correlation of +0.63.

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LO 1.10 Correlational technique

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LO 1.10 Correlational technique

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or

Correlation and Causation

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LO 1.10 Correlational technique

Correlation does NOT prove causation

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Correlation Coefficient Interpretation

Coefficient

Range

Strength of

Relationship

0.00 - 0.20 Very Low

0.20 - 0.40 Low

0.40 - 0.60 Moderate

0.60 - 0.80 High Moderate

0.80 - 0.90 High

0.90 - 1.00 Very High

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Illusory Correlation

The perception of a relationship where none exists. Parents conceive children after adoption.

Confirming evidence

Disconfirming evidence

Do not

adopt

Disconfirming evidence

Confirming evidence

Adopt

Do not conceiveConceive

Michael N

ewm

an Jr./ Photo Edit

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Order in Random Events

Given large number of random outcomes, a few are likely to express order.

Angelo and Maria Gallina won two California lottery games on the same day.

Jerry Telfer/ S

an Francisco C

hronicle

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Experimentation

The backbone of research in psychology.

Experiments isolate causes and their effects.

Exploring Cause and Effect

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Many factors influence our behavior. Experiments (1) manipulate factors that interest us while keeping other factors

under (2) control.

Effects generated by manipulated factors isolate cause and effect relationships.

Exploring Cause & Effect

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The Experiment• Operational definition - definition of a

variable of interest that allows it to be directly measured.

• Independent variable (IV) - variable in an experiment that is manipulated by the experimenter.

• Dependent variable (DV) - variable in an experiment that represents the measurable response or behavior of the subjects in the experiment.

Experimental approach and terms

IV: Violent TV

Definition: Aggressive play

DV: Aggressive play

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For example, to study the effect of breast feeding on intelligence. Breast feeding is the independent variable.

For example, the effect of breast feeding on intelligence - intelligence is the dependent variable.

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In evaluating drug therapies it is important to keep the patients and

experimenter’s assistants blind to which patients got real treatment and which

placebo.

Evaluating Therapies

Double-blind Procedure

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Assigning participants to experimental (Breast-fed) and control (formula-fed)

conditions by random assignment minimizes pre-existing differences

between the two groups.

Evaluating Therapies

Random Assignment

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Random Assignment

SAMPLE

Control Group

Experimental Group

Test for Differences

LO 1.11 Experimental approach and terms

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Confounding Variables

SAMPLE

Control Group

Experimental Group

Are differences due to manipulation or confounding

variable (mood)?

LO 1.11 Experimental approach and terms

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Effect of violent tv on aggression

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No Confounding Variables

SAMPLE

Control Group

Experimental Group

Differences due to manipulation, not an extraneous variable because

mood randomly determined.

LO 1.11 Experimental approach and terms

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Effect of violent tv on aggression

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LO 1.11 Experimental approach and terms

The Experiment

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ExperimentationA summary of steps during experimentation.

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ComparisonBelow is a comparison of different

research methods.