Psychology Ch 2 (The Research Enterprise in Psychology)

Goals of the scientific method

Measurement and description, understanding and prediction, and application and control

Measurement and description

Develop ways to measure and describe behavior

Understanding and prediction

Determine why behavior occurs and predict future behavior

Application and control

Use research findings to solve practical problems

Scientific method

Uses systematic observation to test ideas and theories

Scientific method process

Theory → Hypothesis → Research → Results → Evaluate theory

Theory

A system of related ideas used to explain observations

Hypothesis

A specific, testable prediction about what should occur under certain conditions

Operational definition

Describes exactly how a variable will be measured or manipulated

Experiment

Research method in which a researcher manipulates one variable, observes its effect on another, and controls other factors as much as possible

Purpose of experiments

Determine cause-and-effect relationships

Independent variable (IV)

Variable the researcher manipulates or changes

Independent variable shortcut

IV = I change it

Dependent variable (DV)

Variable the researcher measures that is expected to be affected by the independent variable

Dependent variable shortcut

DV = Data being measured

Experimental group

Group that receives the treatment or manipulation being studied

Control group

Group that does not receive the treatment and provides a comparison for the experimental group

Extraneous variables

Variables other than the independent variable that could affect the dependent variable

Examples of extraneous variables

Amount of sleep, age, previous experience, and environment

Confounding variable

An extraneous variable that changes along with the independent variable, making it difficult to determine what caused the results

Random assignment

Randomly placing participants into experimental or control groups so each participant has an equal chance of entering either group

Purpose of random assignment

Helps make experimental and control groups similar before the experiment begins

Random assignment vs. random sampling

Random assignment determines which experimental group participants enter; random sampling determines who is selected to participate

Correlation

Relationship between two variables

Correlation coefficient

Number represented by r that indicates the strength and direction of a correlation

Range of correlation coefficient

-1.00 to +1.00

Correlation coefficient number

Indicates the strength of the relationship

Correlation coefficient sign

Indicates the direction of the relationship

Positive correlation

Two variables move in the same direction

Positive correlation example

More study time → higher test scores

Negative correlation

Two variables move in opposite directions

Negative correlation example

More absences → lower grades

Zero correlation

No consistent relationship between two variables

Strong correlation

Correlation coefficient close to +1.00 or -1.00

Weak correlation

Correlation coefficient close to 0

r = +.90

Strong positive correlation

r = +.20

Weak positive correlation

r = 0

No correlation

r = -.20

Weak negative correlation

r = -.90

Strong negative correlation

Correlation and causation

Correlation does not prove that one variable causes another

Third-variable problem

A third factor may be responsible for the relationship between two correlated variables

Directionality problem

When two variables are correlated, it may be unclear whether A causes B or B causes A

Naturalistic observation

Researchers observe behavior in its natural environment while trying not to interfere

Advantage of naturalistic observation

Behavior is more realistic

Disadvantage of naturalistic observation

Researchers have little control over variables

Case study

In-depth investigation of one person or a small group

Advantage of case studies

Can provide detailed information

Disadvantage of case studies

Findings may not apply to everyone

Survey

Research method using questionnaires or interviews to collect information

Advantage of surveys

Can collect information from many people quickly

Problems with surveys

Dishonesty, poor memory, wording of questions, and social desirability

Descriptive statistics

Statistics used to summarize and describe data

Mean

Average calculated by dividing the sum of scores by the number of scores

Median

Middle score when scores are arranged from lowest to highest

Mode

Score that occurs most frequently

Variability

Shows how much scores differ from one another

Standard deviation

Measures how much scores vary around the mean

Small standard deviation

Scores are close together

Large standard deviation

Scores are spread out

Inferential statistics

Used to determine whether findings from a sample can be generalized to a larger population

Statistical significance

Observed results are unlikely to have occurred just by chance

Does statistical significance mean an effect is large or important?

No; statistical significance does not necessarily mean the effect is large or important

Population

Entire group researchers want to understand

Sample

Smaller group from the population that is actually studied

Representative sample

Sample that closely resembles the population being studied

Why is a representative sample important?

Makes it easier to generalize findings to the population

Sampling bias

Occurs when a sample is not representative of the population

Placebo

Inactive or fake treatment

Placebo effect

Participants' expectations cause them to experience a change even though they did not receive the actual treatment

Experimenter bias

Researchers' expectations unintentionally influence participants or results

Double-blind procedure

Neither participants nor researchers interacting with them know who received the real treatment

Purpose of double-blind procedure

Helps reduce placebo effects and experimenter bias

Social desirability bias

Participants give answers that make themselves look more socially acceptable instead of answering truthfully

Response set

Tendency to answer questions in a particular way regardless of what is being asked

Human research ethics

Minimize harm, protect privacy, maintain confidentiality, obtain informed consent, allow withdrawal, and explain the study afterward when appropriate

Informed consent

Participants receive enough information to make an informed decision about whether to participate

Deception

Withholding the entire purpose of a study when revealing it could influence behavior; it must be justified and follow ethical standards

Debriefing

Researchers explain the true purpose of a study afterward, especially when deception was used

Animal research

Used when research cannot reasonably be performed on humans

Animal research ethics

Minimize pain and distress, provide appropriate care, and follow ethical guidelines