Research Methods – Introduction to Psychology (Lecture 2)

Vocabulary flashcards covering key terms and concepts from Lecture 2 on Research Methods in PSY100H1.

Variable

An attribute that differs across people, places, or timepoints (e.g., thoughts, feelings, behaviours).

Conceptual Variable

A theoretical construct that cannot be directly observed or proven to be real (e.g., intelligence, attraction).

Operational Definition

The specific procedure or test used to measure a conceptual variable in a given study.

Construct Validity

The degree to which an operational definition truly measures the conceptual variable it claims to measure.

Reliability

Consistency of a measure; includes test-retest reliability and inter-rater reliability.

Test-Retest Reliability

Stability of test scores when the same measure is administered to the same people at different times.

Inter-Rater Reliability

Agreement among independent observers or scorers on a given measure.

Validity vs. Reliability

Reliability is about consistency; validity is about accuracy (a reliable test can still be invalid).

Intelligence Quotient (IQ)

A composite score derived from multiple cognitive subtests to approximate the conceptual variable of intelligence.

Mean

The arithmetic average of all scores in a distribution; sensitive to outliers.

Median

The middle value that separates the higher half of scores from the lower half; resistant to outliers.

Mode

The most frequently occurring score in a distribution.

Standard Deviation (SD)

A statistic that quantifies the typical amount a score deviates from the mean.

Range

The numerical distance between the highest and lowest scores in a data set.

Normal Distribution

A symmetric, bell-shaped curve where mean = median = mode and 68 % of values lie within ±1 SD.

Skewed Distribution

A distribution in which scores pile up at one end and taper off at the other; can be positive or negative.

Outlier

A score at least about 2 SDs from the mean that can distort statistical analyses.

Descriptive Research

Systematic observation of variables without manipulation; cannot determine causation.

Case Study

Intensive examination of a single individual; useful for rare phenomena but hard to generalize.

Survey

Collecting self-report data from large samples via questionnaires or interviews.

Naturalistic Observation

Observing behaviour in its natural context without researcher intervention.

Correlation

A statistic showing the strength and direction of a linear relationship between two variables.

Correlation Coefficient (r)

Numeric index (−1 to +1) expressing correlation strength; higher absolute values indicate stronger relationships.

Pearson r

The most common correlation coefficient for continuous variables.

Non-Linearity

A relationship that is curved or otherwise not straight, making Pearson r misleading (e.g., arousal vs. performance).

Third Variable Problem

A separate factor that causes both variables, producing a misleading correlation.

Spurious Correlation

An apparent association between variables that arises purely by chance.

Hypothesis

A simple, clear, testable prediction derived from evidence and theory.

Independent Variable (IV)

The factor manipulated by the researcher to examine its causal effect.

Dependent Variable (DV)

The outcome measured to assess the impact of the IV.

Random Assignment

Randomly placing participants into experimental groups to equalize other variables.

Experimental Method

A controlled procedure that manipulates at least one IV while holding others constant to infer causation.

Quasi-Experiment

A study with at least one non-randomly assigned IV (e.g., pre-existing groups like MDD vs. control).

Between-Subjects Design

Different participants experience different levels of the IV.

Within-Subjects Design

The same participants experience all levels of the IV (e.g., pre- and post-test).

Mixed Design

Combines between-subjects and within-subjects factors in one study.

Sampling Bias

Systematic differences between the study sample and the population of interest that limit generalizability.

WEIRD Problem

Over-reliance on Western, Educated, Industrialized, Rich, Democratic samples (~12 % of world population).

Confounding Variable

An uncontrolled factor related to the IV or DV that could explain observed effects.

Demand Characteristics

Cues that lead participants to guess a study’s purpose and alter behaviour accordingly.

Observer (Hawthorne) Effect

Changes in behaviour resulting from awareness of being observed.

Placebo Effect

A change in outcome produced by participants’ expectations rather than an active treatment.

Single-Blind Study

Participants do not know whether they are receiving the treatment or placebo.

Double-Blind Study

Both participants and researchers are unaware of who receives which treatment, minimizing bias.

Experimenter Effect

Unintentional influence of a researcher’s expectations on participants’ behaviour or data interpretation.