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Introducing Psychology Ch. 2

STUDY
PLAY
empiricism
originally a Greek school of medicine that stresses the importance of observation and now generally used to describe any attempt to acquire knowledge by observing objects or events
method
a set of rules and techniques for observation that allow researchers to avoid the illusions, mistakes, and erroneous conclusions that simple observation can produce
operational definition
a description of an abstract property in terms of a concrete condition that can be measured
measure
a device that can detect the measurable events to which an operational definition refers
electromyograph (EMG)
a device that measures muscle contractions under the surface of a person's skin
validity
the characteristic of an observation that allows one to draw accurate inferences from it
reliability
the tendency for a measure to produce the same result whenever it is used to measure the same thing
power
the tendency for a measure to produce different results when it is used to measure different things
case method
a method of gathering scientific knowledge by studying a single individual
population
the complete collection of participants who might possibly be measured
sample
the partial collection of people who actually were measured in a study
demand characteristics
those aspects of an observational setting that cause people to behave as they think an observer wants or expects them to behave
naturalistic observation
a method of gathering scientific knowledge by unobtrusively observing people in their natural environments
double-blind observation
an observation whose true purpose is hidden from the researcher as well as from the participant
correlation
the "co-relationship" or pattern of covariation between two variables, each of which has been measured several times
variable
a property whose value can vary or change
third-variable correlation
the fact that two variables may be correlated only because they are both caused by a third variable
matched samples
an observational technique that involves matching the average of the participants in the experimental and control groups in order to eliminate the possibility that a third variable (and not the independent variable) caused changes in the dependent variable
matched pairs
an observational technique that involves matching each participant in the experimental group with a specific participant in the control group in order to eliminate the possibility that a third variable (and not the independent variable) caused change in the dependent variable
third-variable problem
the fact that the causal relationship between two variables cannot be inferred from the correlation between them because of the ever-present possibility of third-variable correlation
experiment
a technique for establishing the causal relationship between variables
independent variable
the variable that is manipulated in an experiment
experimental group
one of the two groups of participants created by the manipulation of an independent variable in an experiment; it is exposed to the stimulus being studied.
control group
one of the two groups of participants created by the manipulation of independent variable in an experiment that is not exposed to the stimulus being studied
dependent variable
the variable that is measured in a study
internal validity
the characteristic of an experiment that allows one to draw accurate inferences about the causal relationships between an independent and dependent variable
external validity
a characteristic of an experiment in which the independent and dependent variables are operationally defined in a normal, typical, or realistic way
theory
a hypothetical account of how and why a phenomenon occurs, usually in the form of a statement about the causal relationship between two or more properties. leads to a hypothesis.
hypothesis
a specific and testable prediction that is usually derived from a theory.
random sampling
a technique for choosing participants that ensures that every member of a population has an equal chance of being included in the sample
informed consent
a written agreement to participate in a study made by a person who has been informed of all the risks that participation may entail
debriefing
a verbal description of the true nature and purpose of a study that psychologists provide to people after they have participated in the study