Chapter 2: Psychology's Scientific Method

Vocabulary flashcards covering the scientific method, research designs, statistics, validity, bias, ethics, and related concepts from the chapter.

Scientific Method

A systematic process for testing theories about the natural world, involving observation, hypothesizing, testing, drawing conclusions, and evaluating the theory.

Theory

A system of ideas that explains observations and makes predictions about future observations; theories can be supported, rejected, or refined by the scientific method.

Hypothesis

A testable prediction derived from a theory.

Operational Definition

A precise description of how a variable will be measured or manipulated in a study.

Independent Variable

The variable that the researcher manipulates in an experiment to study its effect.

Dependent Variable

The variable measured to assess the effect of the independent variable.

Experimental Group

The group that receives the experimental manipulation.

Control Group

The group that does not receive the manipulation, used for baseline comparison.

Random Assignment

Randomly assigning participants to groups to ensure equivalence and control for confounds.

Descriptive Statistics

Statistical procedures used to describe data (mean, median, mode, etc.) without inferring about a population.

Inferential Statistics

Statistical procedures used to draw conclusions about a population from sample data (often with p-values).

Mean

The average value; sum of scores divided by the number of scores.

Median

The middle value when data are arranged in order.

Mode

The most frequently occurring value in a data set.

Range

The difference between the highest and lowest values in a data set.

Standard Deviation

A measure of how spread out scores are around the mean.

External Validity

The extent to which study results generalize to real-world settings.

Internal Validity

The extent to which observed effects are due to the manipulation of the independent variable, not confounds.

Bias

Systematic errors that can skew results, including experimenter and participant biases.

Demand Characteristics

Cues that influence participants to guess the study's purpose and respond accordingly.

Placebo Effect

Behavior change due to a participant's belief that they are receiving treatment.

Double-Blind

An experimental design where neither participants nor researchers know group assignment, reducing bias.

Population

The entire group about which conclusions are drawn in a study.

Sample

The portion of the population actually observed in a study.

Representative Sample

A sample whose characteristics closely match the population, reducing bias.

Random Sample

A sampling method where each member of the population has an equal chance of selection.

Descriptive Research

Research aimed at describing phenomena through observation, surveys, interviews, or case studies; does not explain why.

Correlational Research

Research aimed at identifying relationships between variables; uses correlation coefficient r to indicate strength and direction.

Correlation Coefficient (r)

A statistic ranging from -1.00 to 1.00 that describes the strength and direction of a linear relationship.

Scatter Plot

A graph showing the relationship between two variables.

Correlation Does Not Equal Causation

A relationship between two variables does not prove that one causes the other; third variables or reverse causation may be involved.

Causation

A relationship where one variable directly causes changes in another, often established through experimental manipulation.

Third Variable Problem

An unmeasured variable that could account for the observed relationship between two variables.

Experimental Research

Research design that tests for cause-and-effect by manipulating an independent variable and using random assignment.

Random Assignment (revisited)

Assigning participants to groups by chance to ensure equivalence and control for confounds.

Alpha Level (α = 0.05)

A threshold for statistical significance; if p < .05, results are considered statistically significant.

p-value

The probability of obtaining the observed data, or more extreme, if the null hypothesis is true; used to assess significance.

Reliability

Consistency of a measurement or result across time or items.

Replication

Repeating a study or experiment to see if results hold across samples and conditions.

Meta-analysis

A statistical technique that combines results from multiple studies to draw a broader conclusion.

Ethics in Research (APA Guidelines)

Standards including informed consent, confidentiality, debriefing, and appropriate use of deception.

IRB

Institutional Review Board; committee that reviews research proposals to protect participants' rights and welfare.

Informed Consent

Ethical requirement that participants are informed about the study and voluntarily agree to participate.

Confidentiality

Keeping participants' data private and secure.

Debriefing

Providing participants with full explanations after a study, especially when deception was used.

Animal Research

Use of animals in research with standards for housing, feeding, and welfare; used to benefit humans.