AP Psychology

Ms. SimonSeptember 17-24, 2009

Introduction to Research Methods

Hindsight Bias

The tendency to believe, after learning an outcome, that one would have foreseen it

Scientific Theories

• Set of principles that organize and predict behaviors or events

• Link observed facts

• Imply hypotheses that offer testable predictions

Subfields of Psychology

• Basic Psychology- research

• Applied Psychology- research put into practice as therapist

• Psychiatry- a medical field- deals with mental disorders- prescribe medication

There are three main types of research methods in psychology: Descriptive

Correlational

Experimental

Descriptive Study:

1) Case Study- psychologists study one individual in great depth in hopes of revealing universal principles

Case Study Pros• Detailed information

• Unusual Cases

• Inexpensive

• Few ethical considerations

The Problem with the Case Study:

An individual may be atypical

Cannot generalize results

Difficult to Manipulate Variables

Difficult to quantify data

Naturalistic Observation• Observe subjects in natural

habitats without interacting

Naturalistic Observation

Pros ConsRealistic No manipulat-Inexpensive Ion of

variablesFew ethicalconsideration

Observer Bias

Survey Method• Relies on questions answered by a

group of people in interviews or questionnaires

Survey Method• Experimenter must identify the

population to study

• Random sampling picking members from a population randomly to ensure a representative sample

Survey Method

Pros ConsCan gather lots of data

Honest answers?

Few ethical considerations

Need many participants

Inexpensive Wording Effects

Wording Effects

• In a study by AMNH, 88% of all respondents said that they were interested in plants and trees, but only 39% said they were interested in botany.

• One out of five Americans (22 percent) doubted that the Holocaust had occurred. 12% said they weren’t sure

What to Watch for…

• Order of choices

• Is the time frame specified?

• How personal or direct is the wording?

• Is there a cultural bias?

Correlational Studies

• Correlational studies assess the association between two or more characteristics of interest without ascribing causes

• Is a correlational study an experiment?

Correlation coefficient

Example: R= + .37

Correlational Studies

Correlational Studies

Pros ConsInexpensive Confounding

variablesFew ethical considerations

Illusory correlation

Time Does notObjective I mply

causation

Illusory Correlation

• When we believe there is a relationship between two things, we are likely to notice and recall instances that confirm our belief

What is the correlation?• 1) good looks/popularity • 2) self-esteem/depression • 3) brain size/intelligence • 4) money/happiness • 5) Education/length of life

Correlation: determining causation There is a strong

correlation between people who ate oatmeal for breakfast as a child and cancer versus people who ate Frosted Flakes for breakfast as a child

Friday’s Exam: What to Study

• About 40% Historical Approaches, 60% Research Methods

• Study mostly from Class Discussion!

• Format: Multiple Choice, One short AP exam style essay question, short answer and/or matching

Research Methods

Descriptive Correlational ExperimentalExplains behavior using natural observations

assess the association between two or more characteristics of interest

Researcher manipulates one variable and observes the effect on another variable

1) Case studies2) Naturalistic3) Surveys

1) Causation2) Illusory correlation3) Correlational Coefficient

Experimental DesignConfounding Variables, double-blind

Experimental Method• Researcher manipulates one

variable (independent variable) and observes the effect on another variable (dependent variable)

• Allows one to show a causal relationship

• Q: How is the experimental group different from the control group?

• A: The experimental group receives or reacts to the independent variable and the control group does not receive the independent variable

• Q: Why is a control group needed?

• A: Provides baseline for comparison

Confounding variable:

external differences between the experimental group and the control group other than those

resulting from the independent variable

Confounding Variables

1) Placebo Effect experimental results caused by

expectations alone

Confounding Variables

• Demand Characteristics- participants form an interpretation of the experiment's purpose and unconsciously change their behavior accordingly

How can we control for confounding variables?

How can we control for confounding variables?

1) Random Assignment method of assigning subjects to groups to

minimize pre-existing differences between those groups

This is an example of Between subjects design: Participants in the experimental and control group are different individuals

How can be control for confounding variables?

2) Within subjects design Technique where subjects serve as control and

experimental group.

3) Twin Studies:

Confounding Variables

• Experimenter bias- researcher’s expectations about the outcome of a study influence the results

Q: How can we eliminate experimenter bias?

How can we eliminate experimenter bias?1. Multiple Experimenters

2. Double blind procedure- research design in which neither the experimenter or the participants know who is in the experimental versus control group

AP Psychology

Ms. SimonSeptember 24, 2009

Experimental Statistics

Do Now:

• From your reading: Why do we need operational definitions?

How do psychologists present data?• Frequency Distributions

Statistics• Statistical significance (p) is the

likelihood that the observed difference between groups results from a real difference rather than chance alone

• What’s a good p value?

When is data statistically significant?

1) Large difference between the two means

) Large difference between the two means

When is data statistically significant?

When is data statistically significant?

2) Small standard deviations

But… what’s a standard deviation?

A standard deviation is the degree by which a score varies from the mean

You don’t need to know the equation!

When is data statistically significant?

When is data statistically significant?

3) Large Sample Size

Mean, Median, Mode

6, 7, 8, 9, 10, 10, 10, 11, 11, 11, 11, 12, 12, 13

What’s the mode?

What’s the median?

Normal Distribution

Skewed Data

Homework:

• Activity: design an experiment to see if aggression is related to violent TV watching

Be sure to address random selection, random assignment, experimental versus control group, confounding variables, and how you will minimize the effects of experimental and observer bias.