Readings and Overview
||Objective 2: Identify the
designs used in nursing research: Descriptive, correlational,
quasi-experimental, and experimental study designs. (Objective 3
covered later in Topic 2.)
What types of research
designs are used in nursing research?
Research designs can be divided in to two broad
- Non-experimental research – In this category the
observes the phenomena as they occur naturally and does not intervene
in any way. Types of designs in this category include:
- Descriptive research
- Correlational research
- Experimental research - In this category the
plays an active role by manipulating the independent variable (IV) in
the form of delivery of a treatment or intervention. Experimental
research is conducted to examine cause and effect. Two types of
design fall into this category:
- Experimental research –The following three
elements must be present in a study for it to be considered an experimental
Random assignment of subjects to the
control/comparison group or the experimental group
- Manipulation of the IV by the researcher
- Control of the research setting and situation by
- Quasi-experimental research – Because of the
ethical nature of conducting studies with human subjects, often an experimental
design is not feasible. The quasi-experimental design
- Manipulation of the IV by the researcher,
but it may lack:
- A control group. However, in quasi-experimental
design there is a nonequivalent comparison group. It is
called a comparison group, instead of control group
because members of the group were not randomly assigned to experimental
or control conditions. Thus, there is no assurance that subject
characteristics are equally and randomly distributed between groups,
and this introduces a potential source of error.
- Control of the research setting and situation.
||Objective 3: Explore the
used in nursing research: Descriptive, correlational,
quasi-experimental, and experimental study designs.
What designs are frequently
used in nursing research studies?
- Typical Descriptive Design: Examines characteristics of
a single sample (explores aspects of phenomena of interest).
- Comparative Descriptive Design: Compares two or more
groups that occur naturally in a setting (explores for differences).
- Case Study: Intensive exploration of a single unit of
study (a person, family, group, community, or institution).
- Longitudinal descriptive (not covered in the book):
sample of individuals over time to examine patterns of change, growth,
or trends across time.
- Descriptive Correlational Design: Describes the
relationship among variables in a particular sample.
- Multifactorial Correlational (not covered in the
Because we know reality in the world is multicausal, that is, there are
many factors that influence an outcome, most correlational studies now
are multifactorial and examine correlations between more than 2
- Predictive Correlational: Attempts to explore what
(have an influence on) another variable. Because this design explores
causality, the term independent variable is used to describe
the predictor variables that are thought to predict the outcome
variables (often called the dependent variable). (Please note: This
use of the terminology independent variable and dependent
variable is confusing because the terms have a much more exact
meaning in quasi and experimental designs).
- These studies can be done prospectively (with all data
the same time), but this is not a strong design. A strong design for a
predictive correlational study collects data on the independent
(predictor) variables at one point in time then examines the extent to
which these variables relate to (predict) an outcome at another point
- Model Testing Design: This design is similar to a
predictive correlational design but
is testing a hypothesized causal model. It requires a larger
sample size and very tight measurement of variables. (Read this, but
YOU ARE NOT RESPONSIBLE FOR LEARNING IT FOR THE MIDTERM.)
- Similar to experimental design, but does not have the
same level of
control (e.g., are not able to control as many threats as possible).
Aspects that might not be controlled are:
- Not having a control group to which to compare
- Not randomly assigning participants to control or
- Not having control over the intervention (e.g.,
using an intervention that is in place in practice).
- Many different quasi-experimental designs exist. You are responsible for understanding the concepts that
make such a design different.
You do not need to memorize each of the many different types of
- Provides the best method possible to examine a cause
situation. Provides the greatest amount of control for examining
causality. Tries to reduce or eliminate (almost impossible) all
factors that influence the dependent (outcome) variable other than the
intervention (the independent variable). This is done by:
- Sample selection for homogeneity (which we will
- Random sampling (randomly enrolling individuals
from the population
is not usually possible in health studies—we usually have a convenience
- Random assignment of participants into control and
group (so every eligible person has an equal chance of being assigned
to the experimental/intervention or the control group—thereby
theoretically evenly distributing into each group any characteristics
of the sample that might have an impact on the outcome variable)
- Controlling the intervention as tightly as possible
and controlling as many other extraneous variables as possible.
- Experimental designs are varied. You
responsible for understanding the standard randomized pretest post-test
design with control and experimental group and randomized clinical
trials. (You may skip factorial designs.)
- Additional Points
- Retrospective versus Prospective -
- Descriptive and correlational studies can be retrospective
(this means that the data being analyzed was either collected in the
past as in chart data or that the data collection focuses on the past.
Example: Interviewing mothers of 3-year-old prematurely-born children
about their experiences when these children were in the NICU.
- Prospective means that the data was
collected after the study was designed and focuses on the here and now.
- Longitudinal - Almost any design can be
- This means that data were collected over time, not
just once or twice.
- Descriptive longitudinal studies collect data from
phenomena over weeks, months, or years. Many developmental studies are
descriptive longitudinal studies that continue for the lifetime of the
- These data are used descriptively and also are used
different correlational, and especially multifactorial correlational,
analyses to explore factors that influence positive and problematic
- Experimental and quasi-experimental studies can
data longitudinally to determine whether the experiment (intervention,
independent variable) has a long-term effect.
Learning research can be difficult because it is not exactly black
which would make it easier to comprehend. Designs are not as
rigidly defined as the book indicates. A study can use a combination of
designs (most sophisticated studies do). As noted above, a longitudinal
descriptive study of developmental outcomes is undoubtedly going to
also be a correlational study and will likely conduct predictive
correlational analyses with their data.
Match the title, purpose, or question with
the study design.
Comparative Descriptive Design
Model Testing Design
Predictive Correlational Design
Typical Descriptive Design
The purpose of this study is to
as a predictor of disease management (Clark & Dodge, 1999) ____
Are there differences in personal
women who participate in cardiac rehabilitation and women who do not?
Myocardial infarction survivors: Age
differences in physical health, psychosocial state, and regimen
Taylor, & Abele, 1991) ______
Older adults and exercise: Path
self-efficacy related constructs (Conn,
What are the effects of an extensive
management intervention following cardiac rehabilitation? (Lear,
Laquer, Pritchard, & Frolich, 2001) _______
Will medical regimen adherence and
increase more in patients in the nursing intervention group compared
patients in the control group? (Miller et al., 1988) _________
The aim of this study is to describe
strategies, and social support experienced by survivors of first-time
their spouses (Stewart, Davidson, Meade, Hirth, & Makrides, 2000).
The purpose of this study was to
document patterns of
outpatient cardiac rehabilitation use and identify factors predicting
(Evenson, Rosamond, & Luepker, 1998). This design has two aspects
answers apply. ___________
The purpose of this study was to
determine the effects
of a 12-week cardiac rehabilitation exercise program on the motivation
lifestyle of persons recovering from a recent heart attack or
diagnosis (Song & Lee, 2001) ___________
men and women patients compare on measures
of adjustment, activity, and tangible social support six months post
infarction? (Rose, Suls, Green,
Lounsbury, & Gordon, 1996) _________