AP Psychology - Unit 0 Vocabulary - Chapter 2 Vocabulary #2

Control group

Subjects in a study who do not receive the special treatment given to the experimental group

Extraneous variables

Any variables other than the independent variable that seem likely to influence the dependent variable in a specific experiment

Confounding variables

A condition that exists whenever two variables are linked together in a way that makes it difficult to sort out their specific effects

Random assignment

A procedure in which all subjects in a study have an equal chance of being assigned to any group or condition

Correlation

A correlation exists when two variables are related to each other

Naturalistic observation

A descriptive research method in which the researcher engages in careful, usually prolonged, observation of behavior without intervening directly with the subjects

Reactivity

Alteration of a subject’s behavior due to the presence of an observer

Case study

An in-depth investigation of an individual subject

Survey

A descriptive research method in which researchers use questionnaires or interviews to gather information about specific aspects of participant background, attitudes, beliefs, or behavior

Replication

The repetition of a study to see whether the earlier results are duplicated

Meta-analysis

A research analysis of a study to see whether the earlier results are duplicated

Sample

The collection of subjects selected for observation in an empirical study

Population

The larger collection of animals/people from which a sample is drawn and that researchers want to generalize about

Sampling bias

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

Placebo effect

Occurs when subjected expectations lead them to experience some change even though they receive an empty, fake, or ineffectual treatment

Social desirability effect

A tendency to give socially approved answers to questions about oneself when responding to surveys

Halo effect

Phenomenon that occurs in self-reports when someone’s overall evaluation of person, object, or institution spills over to influence more specific ratings

Double-blind study

A research strategy in which neither subjects nor experimenters knows which subjects are in the experimental or control groups

Statistics

The use of mathematics to organize, summarize, and interpret numerical data

Frequency distribution

An orderly arrangement of scores indicating the frequency of each score or group of scores

Histogram

A bar graph that presents data from a frequency distribution

Frequency polygon

A line figure used to present data from a frequency distribution

Descriptive statistics

Statistics that are used to organize and summarize data

Median

The score that falls exactly in the center of a distribution of events

Mean

The average of the scores in a distribution

Mode

The score that occurs most frequently in a distribution

Negatively skewed distribution

A distribution in which most scores pile up at the high end of the scale

Positively skewed distribution

A distribution in which most scores pile up at the low end of the scale

Variability

The extent to which the scores in a data set tend to vary from one another and from the mean scores

Standard deviation

An index of the amount of variability in a set of data

Normal distribution

A symmetric, bell-shaped curve that represents the pattern in which many characteristics are dispersed in the population

Percentile score

A figure that indicates the percent of people who score at or below the score any one individual has obtained

Correlation coefficient

A numerical index of the degree of relationship between two variables

Scatter diagram

A graph in which paired X and Y scores for each subject are plotted as single points

Coefficient of determination

The percentage of variation in one variable that can be predicted based on the other variable

Inferential statistics

Statistics that are used to interpret data and draw conclusions

Null hypothesis

In inferential statistics, the assumption that there is no true relationship between the variables being observed

Statistical significance

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