UNDERSTANDING
QUANTITATIVERESEARCH
DESIGN
Dr. Anne Snowdon
Professor Lisa High
University of Windsor
QUANTITATIVE RESEARCH
- based on the philosophy of “logical empiricism” or
“positivism”
- Application of logical principles and reasoning
- Researcher adopts a distant and non-interactive
posture = to prevent bias
DEFINE – QUANTITATIVE RESEARCH
 It is a formal, objective, systematic process in which
numerical data is utilized to obtain information about
the world
 It is a method used to describe variables, examine
relationships among variables, and determine causeand-effect interaction between variables
Quantitative Research Design
Involves decisions:
 Will there be an intervention?
 What types of comparison will be made?
 What procedures will be used to control extraneous
variables?
 When and how many times will data be collected
from study participants?
 In what setting will the study occur?
Types of Quantitative Designs
Designs & Major Features:
Control over the “independent variable”
(a)
Experimental
(b)
Quasi-experimental
(a)
Non-experimental
Designs & Major Features
Designs & Major Features:
Type of “group comparisons”
(a)
Between Subjects
(b)
Within Subjects
Designs & Major Features
Designs & Major Features:
Number of “data collection points”
(a)
Cross-sectional
(b)
Longitudinal
Designs & Major Features
Designs & Major Features:
Occurrence of “independent and dependent variable”
(a)
Retrospective
(b)
Prospective
(c)
Descriptive
Designs & Major Features
Designs & Major Features:
“Setting”
(a)
Naturalistic
(b)
Laboratory
Quantitative Designs Discussion
EXPERIMENTAL DESIGN
Characteristics:
(1)
Manipulation – treatment/intervention
(2)
Control – control group/experimental group
(3)
Randomization – random assignment – no systematic
bias
Quantitative Designs Discussion
Types of experimental designs:
(a)
(b)
(c)
(d)
After-only or Post-test only
Factorial Design
Repeated measures design
Clinical trials
Experimental Design
Advantages
Most powerful
Controlling properties
Greater corroboration –
independent variable
affects the dependent
variable
Disadvantages
Number of variables are not
amenable to manipulation
Many variables could
technically be manipulated
but not ethically
Not feasible due to
environmental aspects
Hawthorne Effect
QUASI-EXPERIMENTAL
Types of quasi-experimental designs:
Two most common are:
(a)
Nonequivalent Control-group before-after design
(Pre-test Post-test)
(b)
Time Series Designs
(one-group before-after design)
QUASI-EXPERIMENTAL DESIGN
Advantages
Disadvantages
Practical – not feasible to
conduct true experiments
Lack randomization or control
group features
Introduces some control – full
experimental rigor is not
possible
Cause-and-effect inferences
cannot be made easily – may
alternative explanations for
results
“Rival hypotheses”- one
plausible rival explanaton
NON-EXPERIMENTAL RESEARCH
Types of non-experimental designs:
(a) Ex Post Facto
(Correlational research)
(b)
Retrospective studies
(ex post facto investigations)
(c)
Prospective studies
(case-control design)
(d)
Descriptive
(descriptive correlation study)
NON-EXPERIMENTAL RESEARCH
Advantages
Disadvantages
Nursing – problems not
amenable to experimentation
Inability to reveal causal
relationships conclusively
Correlational efficient &
effective means of large data
collection
Self-selection
Realism is high vs. artificial
Quantitative Research Designs and the “Time
Dimension
Time Series Studies
four situations:
1.
Time-related processes
2.
Time sequenced phenomena
3.
Comparative purposes
4.
Enhancement of research control
CROSS-SECTIONAL STUDIES
Cross-sectional Studies
- data collection at one point in time
- Appropriate for describing the status of a phenomena or
relationships among a phenomena at a fixed point
- Retrospective studies are usually cross-sectional
- Weaker than longitudinal studies
- Main advantage – economical and easy to manage
LONGITUDINAL STUDIES
Longitudinal Studies
- data collected over an extended period of time
- Main value – to demonstrate changes over time – temporal
sequencing = causality
- 3 types: (1) trend studies
(2) panel studies
(3) follow-up studies
Attrition – may cause problems
SPECIFIC TYPES OF QUANTITATIVE
RESEARCH
SURVEY
-self reports
EVAULATIONS
- find out how well a program, treatment, or policy works
- Types of evaluations: (1) process analysis
(2) outcome analysis
(3) impact analysis
(4) cost-benefit analysis
Outcomes Research
- Nursing and allied health disciplines are involved
- Overlaps with evaluation research
- Purpose to document the effectiveness and efficiency of
today’s health care system – to justify care practices, to
improve patient outcomes and costs
- A very global assessment of health care
- Derived from quality assessment and quality assurance
RESEARCH CONTROL TECHNIQUES
-
-
main purpose of quantitative research – maximize control over the research
situation
Confidence that the conditions of the environment are not influencing the data
maintain a true relationship b/w independent and dependent variables
Control external and intrinsic factors
CONSTANCY OF CONDITIONS: controlling “external factors”
(1)
(2)
(3)
minimize situational contaminants – laboratory vs. natural setting?
time control – time of day or year data collected
Communications with study participants – formal research protocols
RESEARCH CONTROL TECHNIQUES
Methods of controlling “Intrinsic Factors”:
(a)
Randomization
(b)
Homogeneity
(c)
Matching
(d)
Statistical control
INTERNAL & EXTERNAL VALIDITY
INTERNAL VALIDITY
Define – the extent to which it is possible to make an “inference”
that the independent variable is truly influencing the dependent
variable
- high degree of validity – experimental vs. quasi-
experimental/correlation why?
INTERNAL & EXTERNAL VALIDITY
Threats to Internal Validity:
(1)
History
(2)
Selection
(3)
Maturation
(4)
Mortality
INTERNAL & EXTERNAL VALIDITY
EXTERNAL VALIDITY
Define – the “generalizability” of the research findings to
other settings or samples
- adequacy of the sampling design
- environmental or the research situation influences a study’s
external validity
Critiquing Quantitative Research Designs
See page 198 – Box 8-1
Suggest to refer to for you term paper
MAKING CONNECTIONS
IDENTIFY THE “INDEPENDENT & DEPENDENT” VARIABLE
(a)
(b)
(c)
(d)
(e)
(f)
Nurses’ attitudes toward mental retardation vary according to their
clinical speciality area.
The type of nursing care primary versus team is unrelated to the
frequency of turning patients.
The incidence of decubitus ulcers is related to the frequency of
turning patients.
Baccalaureate and associate degree nurses differ in use of touch as a
therapeutic device with patients.
First time blood donors experience greater stress during the
donation than donors who have given blood previously.
Surgical patients who give high ratings to the informativeness of
nursing communications experience less level preoperative stress
than do patients who give low ratings.