Case Study
An observation technique in which one person is studied in depth in the hope of revealing universal principles.
Survey
A technique for ascertaining the self-reported attitudes or behaviors of people, usually by questioning a representative, random sample of them.
False Consensus Effect
The tendency to overestimate the extent to which others share our beliefs and behaviors.
Population
All the cases in a group, from which samples may be drawn for a study.
Random Sample
A sample that fairly represents a population because each member has an equal chance of inclusion.
Naturalistic Observation
Observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.
Correlation
A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other. The correlation coefficient is the mathematical expression of the relationship, ranging from-1 to +1.
Scatterplot
A graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter i
Illusory Correlation
The perception of a relationship where none exists.
Experiment
A research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control ot
Double-blind Procedure
An experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.
Placebo Effect
Experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which is assumed to be an active agent.
Experimental Condition
The condition of an experiment that exposes participants to the treatment, that is, to one version of the independent variable.
Control Condition
The condition of an experiment that contrasts with the experimental condition and serves as a comparison for evaluating the effect of the treatment.
Random Assignment
Assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups.
Independent Variable
The experimental factor that is manipulated; the variable whose effect is being studied.
Dependent variable
The outcome factor; the variable that may change in response to manipulations of the independent variable.
Mode
The most frequently occurring score(s) in a distribution
Mean
The arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.
Median
The middle score in a distribution; half the scores are above it and half are below it.
Range
The difference between the highest and lowest scores in a distribution.
Standard Deviation
A computed measure of how much scores vary around the mean score.
Statistical Significance
A statistical statement of how likely it is that an obtained result occurred by chance.