convergent testing A test for construct validity
in which new instruments are administered at the
same time as an instrument known to be valid;
scores of the two instruments are compared,
and strong, positive correlations indicate good
validity
correlated t test A variation of the t test used
when there is only one group or when the groups
are related; paired t test
correlation coefficient An estimate, ranging
from 0.00 to +1.00, that indicates the reliability of
an instrument; a statistic used to describe the rela-
tionship between two variables
correlational designs Nonexperimental designs
used to study relationships among two or more
variables
cost-benefit ratio Comparison of benefits to
potential costs that might result from change
count data The raw number of health phenom-
ena under investigation in epidemiology
covary When change in one variable is associ-
ated with change in another variable
credibility One of four criteria for establishing
a trustworthy qualitative study; refers to the truth
or believability of findings
criterion-related validity Degree to which the
observed score and the true score are related
critical thinking Skill set that involves critical
appraisal of information
Cronbach’s alpha A test for instrument reliabil-
ity used with interval or ratio items; all items are
simultaneously compared using a computer
crossover designs Experimental designs that use
two or more treatments; subjects receive treat-
ments in a random order
cross-sectional Nonexperimental design used to
gather data from a group of subjects at only one
point in time; study design to measure exposure
and disease as each exists in a population or rep-
resentative sample at one specific point of time
cycle of scientific development A model of the
scientific process
data reduction The simplification of large
amounts of data obtained from qualitative inter-
views or other sources
data saturation In qualitative research, the
time when no new information is being obtained
and repetition of information is consistently
heard
Declaration of Helsinki An international stan-
dard providing physician guidelines for conduct-
ing biomedical research
deductive reasoning Thinking that moves from
the general to the particular
degrees of freedom A statistical concept used to
refer to the number of sample values that are free
to vary; n – 1
dependability One of four criteria for a trust-
worthy qualitative study that relates to consistency
in the findings over time; auditability; findings are
reflective of data
dependent variable Outcome or variable
that is influenced by the independent variable;
Y variable
descriptive correlational designs Correlational
design type used to explain the relationship
among the variables or groups using a nondirec-
tional hypothesis
descriptive designs Designs that provide a
picture of a situation as it is naturally happening
without manipulation of any of the variables
descriptive epidemiology Examination of the
distribution of disease in a population in terms of
person, place, and time
descriptive research A category of research that
is concerned with providing accurate descriptions
of phenomena
descriptive statistics Collection and presenta-
tion of data that explain characteristics of vari-
ables found in a sample
descriptive studies Nonexperimental studies
used to provide information about a phenomenon
determinants Factors that are capable of bring-
ing a change in healthGLOSSARY 517