### 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.)

### Critical thinking

thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions.

### Theory

an explanation using an integrated set of principles that organizes and predicts observations.

### Operational definitions

precise statements of the procedures (operations) used to define independent and dependent variables.

### Replication

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

### 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

is the tendency to overestimate the extent to which others share our beliefs and behaviors.

### Random sample

a sample that fairly represents a population because each member has an equal chance of inclusion.

### Naturalistic observation

involves observing and recording behavior in naturally occurring situations without trying to manipulate or control the situation.

### Correlation

a statistical measure that indicates the extent to which two factors vary together and thus how well one factor can be predicted from the other. Correlations can be positive or negative.

### Scatterplot

a depiction of the relationship between two variables by means of a graphed cluster of dots.

### Experiment

a research strategy in which a researcher directly manipulates one or more factors (independent variables) in order to observe their effect on some behavior or mental process (the dependent variables; experiments therefore make it possible to establish cause-and-effect relationships.

### Placebo

an inert substance or condition that is administered as a test of whether an experimental subjects who mistakenly thinks a treatment

### Double-blind procedure

a control procedure in which neither the experimenter nor the research subjects are aware of which condition is in effect. It is used to prevent experimenters' and subjects' expectations from influencing the results of an experiment.

### 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

the procedure of assigning subjects to the experimental and control conditions by chance in order to minimize preexisting differences between the groups.

### Mode

the most frequently occurring score in a distribution; it is the simplest measure of central tendency to determine.

### Mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.

### Range

a measure of variation computed as the difference between the highest and lowest scores in a distribution.

### Standard deviation

the average amount by which the scores in a distribution deviate around the mean. Because it is based on every score in the distribution

### Statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance.