Unit 0: Research Methods

Hypothesis

A tentative explanation that must be testable and falsifiable

Operational Definition

A clear and precise definition of variables that allows replication

Qualitative Data

Descriptive data such as eye color

Quantitative Data

Numerical data used for statistics

Population

The entire group a study could apply to

Sample

The specific people selected for a study

Correlation

A research method that measures relationships between variables

Positive Correlation

Two variables increase or decrease together

Negative Correlation

As one variable increases the other decreases

Directionality Problem

Uncertainty about which variable causes the other

Third Variable Problem

Another variable may explain a relationship

Experiment

Research method that manipulates variables to determine cause and effect

Independent Variable

The variable manipulated by the researcher

Dependent Variable

The measured outcome variable

Experimental Group

The group receiving the treatment

Control Group

The baseline or placebo group

Placebo Effect

Improvement caused by expectations rather than treatment

Double-Blind Study

Neither participants nor researchers know group assignments

Single-Blind Study

Only participants are unaware of their group assignment

Confounding Variable

An unintended factor that affects results

Random Assignment

Assigning participants to groups by chance

Naturalistic Observation

Observing behavior in natural settings

Case Study

In-depth study of one individual or group

Meta-Analysis

Combining results from many studies

Mean

The arithmetic average

Median

The middle score in a distribution

Mode

The most frequently occurring score

Range

Difference between highest and lowest scores

Standard Deviation

Average distance scores vary from the mean

Statistical Significance

Results unlikely due to chance

Effect Size

Measure of the strength of an effect

Regression Toward the Mean

Extreme scores tend to move closer to average over time

Percentile Rank

Percentage of scores below a given score

Confidentiality

Keeping participant information private

Informed Consent

Participants agree to take part after being informed

Debriefing

Explaining the true purpose of a study afterward

Deception

Misleading participants when justified by research goals

Survey

Research method using questionnaires or interviews

Social Desirability Bias

Tendency to answer in socially acceptable ways

Wording Effects

Question phrasing influences responses

Random Sample

Every member of a population has an equal chance to participate

Representative Sample

Sample reflects characteristics of the population

Convenience Sample

Sample chosen based on availability

Sampling Bias

Sample does not accurately represent the population

Experimenter Bias

Researcher expectations influence results

Participant Bias

Participant expectations influence behavior

Confirmation Bias

Seeking evidence supporting existing beliefs

Hindsight Bias

Believing after an event that you predicted it

Overconfidence Bias

Overestimating your knowledge or abilities