ap psych unit 0: 1-36

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.)

hypothesis

a testable prediction, often implied by a theory.

falsifiable

the possibility that an idea, hypothesis, or theory can be disproven by observation or experiment.

operational definition

a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures. (Also known as operationalization.)

replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding can be reproduced.

case study

a non-experimental technique in which one individual or group is studied in depth in the hope of revealing universal principles.

naturalistic observation

a non-experimental technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

random sample

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

population

all those in a group being studied, from which random samples may be drawn. (Note: Except for national studies, this does not refer to a country’s whole population.)

correlation

a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

regression toward the
mean

the tendency for extreme or unusual scores or events to fall back (regress) toward the average.

random assignment

assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups.

independent variable

in an experiment, the factor that is manipulated; the variable whose effect is being studied.

confounding variable

in an experiment, a factor other than the factor being studied that might influence a study’s results.

dependent variable

in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated.

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.

percentile rank

the percentage of scores that are lower than a given score.

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.

normal curve

a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer scores lie near the extremes. (Also called a normal distribution.)

meta-analysis

a statistical procedure for analyzing the results of multiple studies to reach an overall conclusion.

confirmation bias

a tendency to search for information that confirms one’s preconceptions

overconfidence

tendency to be very sure of a fact and then later finding that objective reality was different

positive correlation

a steady relationship between two variables in the same direction

negative correlation

an inverse relationship between two variables

central tendency

the middle of a data set or where the scores in a data set tend to fall (3 measures - mean, median, mode)

sample

a relatively small number of participants drawn from an entire population

representative sample

a group that closely matches the characteristics of its population as a whole.

convenience sampling

a sampling method in which you select a naturally occurring group of people within population

cultural norms

the shared beliefs, values, and behaviors that define appropriate behavior within a culture or society

variation

the existence of qualitative differences in behavior, physiology, structure, and form among individuals in a population

positive skew

When a distribution has a few extreme scores toward the high end relative to the low end

negative skew

When a distribution has a few extreme scores toward the low end relative to the high end

bimodal distribution

a set of scores that have two peaks, or modes, where values are clustered