True/False- Researchers should design studies that are easy for subjects to participate in regardless of
how much control over extraneous variables is achieved. - Nursing’s body of knowledge is dependent on the quality of research findings that are
disseminated.
TEST YOUR KNOWLEDGE 6-4
How did you do? 1. F; 2. T» Quantitative designs are used to describe phenomena, explain relationships, predict relation-
ships, and explain causality.
» Nurses must consider elements of design when appraising quantitative studies.
» There are three major categories of quantitative designs: experimental, quasi-experimental,
and nonexperimental.
» Causality refers to a relationship that exists between a cause and its effect. The IV must occur
prior to the DV in order to claim a cause-and-effect relationship. Because outcomes can have
multiple causes, probability assertions leave open the possibility for multicausality.
» In quantitative designs, researchers control, manipulate, and randomize to control for extra-
neous variables.
» Randomization is used in two ways to control for extraneous variables. Random sampling is the
process of selecting a sample whereby each element in the population has an equal chance
of being selected. Random assignment to groups means that all subjects in the sample have
an equal chance of being assigned to either the intervention or control group.
» Researchers use within-groups designs to examine how subjects in the same group change
over time. Between-groups designs involve comparisons of subjects of one group to subjects
in another group.
» There are two major types of validity: internal and external. Internal validity is the degree to
which one can conclude that it was the IV, not extraneous variables, that produced the change
in the DV. External validity refers to the confidence one has that findings can be generalized
across different types of people, settings, and times.RAPID REVIEW
to groups to reduce this threat. Therefore, it would be important for the re-
searcher to inform subjects during the recruitment process that they will not
be allowed to choose their own groups. Doing so allows individuals to make
informed decisions about participating.
6.4 Keeping It Ethical 167