Hindsight Bias

the tendency to believe, after learning an outcome, that one would have foreseen it. (also known as the i-knew-it-all-along phenomenon)

Theory

an explanation using an integrated set of principles that organized observations and predict behaviors or events

Hypothesis

a testable prediction, often implied by a theory

Operational definition

a statement of the procedures (operations) used to define research variables.

Replication

repeating the essence of a research study, usually with different particiapnts in different situations, to see whether the basic finding estends to other participants and circumstances

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 how well either factor predicts the other. The correlation coefficient is the mathematical expression of the relarionship, ranging from -1 to +1

Scatterplot

a graph 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 indicated high correlation)

Illusory correlation

the perception of a relationship where none exists

Experiment

a research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process. By random assignment of participants, the experimenter aims to control other relevant factors

Double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the researcher participants have received the treatment or the placebo

Placebo effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, assumed to be an active agent

Experimental condition

the condition of an experiment that expose the particpants 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 the 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 different groups

Independent variable

the experimental factor that is manipulated; the variable whose effects are being studied

Dependent variable

the outcome factor; the variable that may change in response to the manipulation 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 the scores 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