- canonical correlation
- A correlation between two sets of variables. The first
canonical correlation is derived by computing the linear
combination of each set of variables that will give the highest
possible correlation. Additional canonical correlations can be
computed using different linear combinations of the variables in
each set. This technique helps scientists to understand complex
relationships between constructs that cannot be easily tapped by
a single measure.

- carry-over effects
- These effects result from of a participant's involvement in
one condition affecting his or her performance in all subsequent
conditions. Carry-over effects occur only in within-subjects
designs.

- case study
- See
*case-study level of constraint*.

- case-study level of constraint
- Research in which minimal constraints are placed on
participants' behavior. Case-study research usually focuses on
the behavior of a single participant.

- case study research
- See
*case-study level of constraint*.

- categorical data
- Synonymous with
nominal data.

- categorical variable
- Synonymous with
discrete variable. A categorical variable can have only a
finite number of values.

- causal hypothesis
- Usual form of the research hypothesis in experimental
research. It states that the independent variable has a causal
relationship to the dependent variable. To accept this
hypothesis, one must have rejected the
null hypothesis and all
confounding-variable hypotheses.

- causal inference
- Conclusion that the change in the independent variable
resulted in a change in the dependent variable. It may be drawn
only if all potential
confounding variables are controlled.

- causal relationship
- A relationship between variables in which one variable
causes a predictable change in the other variable.

- causally related
- Two variables are causally related if a change in one
variable results in a predictable change in the other variable
and the change occurs as a direct result of the action of the
first variable.

- ceiling effect
- See
*scale attenuation effects*.

- central tendency
- Average or typical score in a distribution. Three measures
of central tendency are the
mean,
median, and
mode.

- chi-square
- A statistical distribution that forms the basis for
inferential statistics used with nominal data.

- classification variables
- Organismic or participant variables used to classify
participants into discrete groups. Classification variables are
used for assigning participants to groups in differential
research.

- coding data
- Process by which scores are assigned to behaviors. The coded
data are usually in a form that can be more easily analyzed.

- coefficient alpha
- An index of
internal consistency reliability.

- coefficient of determination
- The square of the Pearson product-moment correlation. It
represents the proportion of variability in one variable that
can be predicted on the basis of information about the other
variable.

- cognitive psychology
- The sub-discipline of psychology that studies perceptual
processing and basic thought processes.

- cognitive science
- A broad field that encompasses several disciplines,
including behavioral neuroscience, neuroanatomy,
neurophysiology, computer science, linguistics, all of which are
interested in modeling and understanding the basic brain
processes.

- cohort effect
- The concept that people of a given chronological age in a
given culture may behave similarly throughout their lives and
different from people of other ages because of shared life
experiences.

- column means
- In factorial designs, one factor is usually illustrated as
separate columns of data, in which each column represents a
different level of the factor. A second factor might be
illustrated as rows of data, in which the different rows
represent levels of the second factor. Column means are computed
by taking the mean of all participants who appear in a given
column regardless of their level on the second factor.

- communication phase of research
- Research phase in which the rationale, hypotheses, methods,
results, and interpretations of the study are presented in oral
or written form to other researchers.

- complete counterbalancing
- See
*counterbalancing*.

- computer-analysis programs
- Sophisticated computer programs for statistical analyses.
Some examples are
*Biomedical Programs (BMDP)*;*Minitab*;*Statistical Analysis System (SAS)*.

- computer file
- A set of information stored digitally and made available to
computers for processing. A computer file can include a program,
data, or output.

- computer modeling
- Using a computer to simulate a psychological process as
close as possible to the way in which it is actually performed
by people.

- concept
- A basic principle that forms the building blocks for
scientific theories.

- conceptual replication
- Repeating a study using different operational definitions
for the variables.

- confidence interval
- An interval in which we predict the population parameter to
fall with a specified level of confidence. For example, a 95%
confidence interval will contain the population parameter 95% of
the time.

- confidentiality
- An ethical requirement in most research; sensitive and
personal information provided by participants should be
protected and made unavailable to anyone other than the
researchers.

- confounded
- Two variables are said to be confounded if they vary
simultaneously so that it is impossible to determine which
variable was responsible for the observed change in the
dependent variable.

- confounding variable
- Any uncontrolled variable that might affect the outcome of a
study. A variable can confound a study only if (1) there is a
mean difference between the groups on the variable and (2) there
is a correlation between the variable and the dependent measure.

- confounding-variable hypothesis
- Actually, a set of hypotheses. Each confounding-variable
hypothesis states that a particular confounding variable is
responsible for the observed changes in the dependent measure.
Each of the hypotheses must be rejected before one can safely
conclude a causal relationship between the independent and
dependent variables.

- constraints
- Restrictions places on the researcher in an effort to
increase the precision of the research and enhance the validity
of the conclusions.

- constants
- Variables that are prevented from varying (i.e., are held
constant).

- construct
- An idea constructed by the researcher to explain observed
events. Constructs are not necessarily direct representations of
reality; that is, they are not facts. They are explanatory
fictions because, in most cases, we do not know the real reason
for a particular event. Once formulated, constructs are used as
if they are true (i.e., analogically) to predict relationships
between variables in new situations.

- construct validity
- Validity of a theory. Most theories in science present a
broad conceptual explanation of relationships among variables
and make many predictions. Construct validity is established by
verifying the accuracy of each possible prediction that might be
made from the theory. Because the number of predictions is
usually infinite, construct validity never can be fully
established. However, the more independent predictions from the
theory verified as accurate, the stronger will be the construct
validity of the theory.

- content analysis
- Classifying behaviors found in naturalistic or archival
records to create data for analysis.

- content items
- In questionnaires and interviews, content items focus on
respondents' opinions, attitudes, and knowledge rather than
factual items that can be independently verified.

- contingency
- A relationship between two or more variables in which the
first event is highly predictive of the occurrence of the second
event. The relationship between the variables is a probabilistic
one and does not necessarily imply a causal connection.

- continuous variable
- Any variable that can theoretically take on an infinite
number of values. Continuous variables are often contrasted with
discrete or categorical variables.

- contrast
- See
*planned comparison*.

- control
- See
*control in research.*

- control group
- A group of participants used in either differential or
experimental research that serves as a basis of comparisons for
other groups. The ideal control group is similar to the
experimental group on all variables except the independent
variable that defines the group.

- control in research
- Any procedure that is designed to reduce confounding.

- control of variance
- Control of
error variance and
extraneous variance in research.

- controlled research
- Research that employs adequate controls to rule out
competing hypotheses and this draw causal conclusions.

- convergent operations
- A term for the agreement or similarity among findings from
different studies that were carried out with different
operational definitions of the same concepts.

- convergent validity
- Occurs when different studies, using different operational
definitions, produce similar findings.

- correlated-groups design
- Research design in which the participants in each of the
groups are related to the participants in the other groups. Two
correlated-groups designs are (1) the
within-subjects design and (2) the
matched-subjects design. These designs provide more powerful
tests of the hypotheses because they control for individual
differences. They are contrasted with independent-groups design.

- correlated-subjects design
- See
*correlated-groups design.*

- correlated
*t*-test (or direct-difference*t*-test or matched-pairs*t*-test) - Statistical procedure used to test for mean differences
between two groups in a within-subjects or matched-subjects
design.

- correlation
- Degree of relationship between two or more variables.

- correlation coefficient
- An index of the degree of relationship between variables.

- correlational level of constraint
- Research designed to quantify the relationship between two
or more variables. There is no manipulation of variables and no
attempt to draw causal inferences.

- correlational research
- Research that seeks to measure the relationship between
variables without trying to determine causality. The term is
sometimes used broadly to include any nonexperimental research
design, such as differential research and quasi-experimental
designs.

- counterbalancing
- Control procedure used in within-subjects designs to control
for
sequence effects. It is most practical when there is a small
number of conditions in the study. With complete
counterbalancing all possible arrangements of conditions are
included; with incomplete counterbalancing only some of the
possible arrangements are included.

- criterion
- The variable that we want to predict in
regression.

- criterion measure
- The variable that we want to predict in
regression.

- critical thinking
- Applying the principles of inference discussed in this
textbook to everyday situations.

- crossover effect
- In quasi-experimental research, a finding in which two
nonequivalent groups show one pattern of scores before the
manipulation and the reverse pattern of scores after the
manipulation. The name derives from the crossing of the lines
when such a result is graphed.

- cross-cultural research
- Exploring psychological phenomena across more than one
culture.

- cross-sectional design
- A design that compares the performance, attitudes, or
histories of people of different ages or at different times in
history. The groups are defined by the age range of the people
in the groups or the historical time in which participants were
tested. In a cross-sectional study, participants appear in only
one group. This design is often contrasted with
longitudinal designs.

- cross-sectional research
- Research in which a cross-sectional research design is used.

- cross-tabulation
- Procedure for organizing frequency data that displays the
relationship between two or more nominal variables. A
cross-tabulation table contains individual cells, with the
number in each cell representing the frequency of participants
who show that particular combination of characteristics.

- cursor
- The symbol on the screen of a personal computer that
indicates where action will take place. The cursor is moved
around the screen a mouse or other pointing device.