Chapter 1 Terms

Anecdotal Evidence

Information or evidence gathered from others or from one’s own experiences.

Case Study

An in-depth investigation of an individual person or a small group of people, often over an extended period of time.

Confounding Variable

See Extraneous Variable.

Constant

A feature or quality that always takes the same value across all situations.

Construct Validity

The extent to which there is evidence that a test measures a particular hypothetical construct.

Control Group

A group of individuals designed to serve as an accurate comparison in an experiment.

Correlation

A measure of the strength of the relationship between two variables.

Correlation Coefficient

A numerical index of the degree of relationship between two variables.

Dependent Variable

A variable that is measured in an experiment.

Descriptive Statistics

Statistics designed to describe the data collected, including mean, median, and standard deviation.

Double-Blind Study

Experiment in which neither the experimenter nor the participants know which group each participant belongs to.

Empiricism

The philosophical perspective that states that knowledge should be gained by direct observation of the world.

Experiment

Scientific tool used to measure the effect of one variable on another.

Experimental Group

The participants in a study who receive the manipulation regarding the independent variable.

Experimenter Bias

Actions made by the experimenter to promote the result they hope to achieve.

Extraneous Variable

A variable that the researcher did not manipulate or measure but could still affect the outcome of the experiment.

Frequency Distribution

A figure that plots values of a variable on the x-axis and the frequency of those values on the y-axis.

Hypothesis

Testable statements guided by theories that make specific predictions about the relationship between variables.

Independent Variable

A variable that is controlled or manipulated in an experiment.

Inferential Statistics

Statistics that allow us to use results from samples to make inferences about overall populations.

Interview

A research tool where the investigator asks the participant questions, often structured or semi-structured.

Levels of Analysis

Different perspectives that emphasize different aspects of a research question.

Mean

Average value of a set of data.

Measures of Central Tendency

Descriptive statistical techniques for summarizing a distribution of data into a single value.

Median

The centre value in a data set when arranged numerically.

Mode

The value that appears most frequently in a data set.

Naturalistic Observation

A descriptive research method where the researcher observes behavior in real-world settings.

Normal Distribution

A distribution with a smooth, bell-shaped curve around a single peak.

Paradigm

A set of assumptions and ideas about what kind of research questions can be asked and how they can be answered.

Ob-ob mouse

A mouse resulting from a genetic mutation associated with extreme obesity.

Operational Definition

Describes the actions or operations to objectively measure or control a variable.

Outlier

A value that lies outside the range of most other values in a data set.

Participants

The persons whose behavior is systematically studied or observed in a study or experiment.

Placebo Effect

When an individual exhibits an effect from a perceived treatment when no treatment is actually given.

Population

The full group of individuals you are seeking to understand.

Practice Effect

Improved performance over the course of an experiment due to increased experience.

Psychological Test

A standardized measure of a sample of a person’s behavior, e.g., IQ test.

Questionnaire

A research tool where a participant responds to a written list of items or questions.

Random Assignment

Assigning participants to either the experimental or control group at random to avoid biases.

Random Sample

Choosing a set of subjects at random from the population being studied.

Raw Data

Data collected from a study that has yet to be assessed using statistical analyses.

Reliability

The measurement consistency of a test or other measurement techniques.

Replication

The repetition of a study to see if earlier results can be duplicated.

Response Set

A tendency of research participants to respond to questions in a particular way unrelated to the content.

Sample

The subset of the population you examine.

Sampling Bias

A problem that occurs when a sample is not representative of the population from which it is drawn.

Scientific Method

The formal methods used to examine and answer questions of a scientific nature.

Social Desirability Bias

A tendency to give socially approved answers to questions about oneself.

Standard Deviation

A measure of the variability of a set of data, specifically the expected difference from the mean.

Statistically Significant

The condition when the probability that observed findings are due to chance is very low.