Quantitative Research Design, Rigor and Validity Discussion This week you are going to critique a journal article that you will select from any resources.

Quantitative Research Design, Rigor and Validity Discussion This week you are going to critique a journal article that you will select from any resources. In order to critique an article, the reader needs to evaluate different aspects of the article. Can we discuss about some of the questions that the reader needs to ask in order to make a proper critique of an article? Chapter 9
Quantitative Research
Design
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Question
Tell whether the following statement is true or false:
Many qualitative nursing studies aim to elucidate
cause-and-effect relationships.
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Answer
False
Many quantitative not qualitative nursing studies aim
to elucidate cause-and-effect relationships.
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Question
Tell whether the following statement is true or false:
Counterfactual is what would have happened to the
same people simultaneously exposed and not
exposed to the causal factor.
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Answer
True
Counterfactual is what would have happened to the
same people simultaneously exposed and not
exposed to the causal factor.
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The Counterfactual Method
• The counterfactual is what would have happened to
the same people simultaneously exposed and not
exposed to the causal factor.
• Effect represents the difference between the two.
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Causality
• The counterfactual method
• Criteria for causality—Lazarsfeld (1955)
1. Temporal
2. Empirical relationship
3. Relationship cannot be explained as
being caused by a third variable
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Experiments or Randomized Controlled
Trial Properties
1. Manipulation
2. Control
3. Randomization
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Manipulation
• Doing something to study participants
• Experimenter manipulates the independent variable
by administering a treatment (intervention) to some
subjects and withholding it from others, or by
administering some other treatment.
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Control Group
• Researchers can expose the control group to
various conditions:
– No treatment
– Alternative treatment
– Placebo
– Standard treatment
– Different doses of the treatment
– Wait list
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Randomization (Random Assignment or
Random Allocation)
• Involves placing subjects into treatment conditions
at random
• Approximates the ideal—but impossible—
counterfactual of having the same people in multiple
treatment groups simultaneously
• Basic randomization
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Question
Tell whether the following statement is true or false:
Some studies involve patient-centered interventions
that are tailored to meet individual needs or
characteristics.
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Answer
True
Everyone in the experimental group usually gets the
same intervention as delineated in formal protocols,
but some studies involve patient-centered
interventions (PCIs) that are tailored to meet
individual needs or characteristics.
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Small Table of Random Digits
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Example of Random Assignment
Procedure
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Stratification
• Divided into groups before randomized
• Permuted block randomization
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Blinding
• Single-blind studies
• Double-blind studies
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Randomization
• Cluster
• Partially randomized patient preference design
• Randomized consent design
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Experimental Designs
• After-only (posttest-only) design
• Before–after (pretest–posttest) design
• Factorial design
• Crossover (repeated measures) design
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Symbolic Representation of a Pretest–
Posttest Experimental Design
R
O1
R
O1
X
O2
O2
R = Randomization
O = An observation or measurement
X = An intervention
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Factorial Designs
• Two or more variables are manipulated
simultaneously.
• Test both main effects and interaction effects
• Randomized block design
• Crossover design
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Quasi-Experimental and
Preexperimental Designs
Nonequivalent control group pretest–posttest design
(quasi-experimental)
O1
X
O2
O1
O2
Nonequivalent control group posttest-only design
(preexperimental)
X
O1
O1
One group pretest-posttest design
(preexperimental)
O1
X
O2
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Quasi-Experimental Designs
• Time series design
• Nonequivalent control group before–after
design
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Time Series Design
O1
O2
O3
O4
X
O5
O6
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O7
O8
Other Quasi-Experimental Designs
• Quasi-experimental dose-response analysis
• Quasi-experimental (nonrandomized) arms of a
PRPP randomization design
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Nonexperimental/Observational Research
• Descriptive research
• Correlational studies
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Designs of Correlational Studies
• Retrospective (case-control) design
• Prospective (cohort) designs
• Natural experiments
• Path analytic studies
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Descriptive Studies
• Prevalence studies
• Incidence studies
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Chapter 10
Rigor and Validity in
Quantitative Research
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Validity and Validity Threats
• Validity: the approximate truth of inference
• Threats to validity are reasons that an inference
could be wrong.
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Types of Validity
• Statistical conclusion validity
• Internal validity
• Construct validity
• External validity
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Controlling Intrinsic Source
of Confounding Variability
• Randomization
• Crossover
• Homogeneity
• Stratification/blocking
• Matching (pair matching)
• Statistical control
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Benefits and Limitations of Control
Methods: Randomization
Benefits:
• Controls all preintervention confounding variables
• Does not require advance knowledge of which
variables to control
Limitations:
• Ethical and practical constraints on variables that
can be manipulated
• Possible artificiality of conditions
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Benefits and Limitations of Control
Methods: Crossover (Repeated Measures)
Benefits:
• If done with randomization, strongest possible
approach
Limitations:
• Cannot be used if there are possible carryover
effects from one condition to another
• History threat may be relevant if external factors
change over time.
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Benefits and Limitations of Control
Methods: Homogeneity
Benefits:
• Easy to achieve in all types of research
• Enhances interpretability of relationships
Limitations:
• Limits generalizability
• Requires knowledge of which variables to control
• Range restriction could lower statistical conclusion
validity.
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Benefits and Limitations of Control
Methods: Stratification
Benefits:
• Enhances the ability to detect and interpret
relationships
• Offers opportunity of examining blocking variable as
an independent variable
Limitations:
• Usually restricted to a few stratifying variables
• Requires knowledge of which variables to control
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Benefits and Limitations of Control
Methods: Matching
Benefits:
• Enhances interpretability of relationships
• May be easy if there is a large “pool” of potential
available controls
Limitations:
• Usually restricted to a few matching variables
• Requires knowledge of which variables to match
• May be difficult to find comparison group matches,
especially if there are more than two matching
variables
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Benefits and Limitations of Control
Methods: Statistical Control
Benefits:
• Enhances ability to detect and interpret relationships
• Relatively economical means of controlling several
confounding variables
Limitations:
• Requires knowledge of which variables to control, as
well as measurement of these variables
• Requires some statistical sophistication
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Four Types of Validity Affect
Rigor of Quantitative Study
• Statistical conclusion validity
• Internal validity
• Construct validity
• External validity
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Statistical Conclusion Validity
• Low statistical power
• Restriction of range
• Unreliable implementation of a treatment
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Intervention Fidelity
• Extent to which the implementation of a treatment
is faithful to its plan
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Internal Validity
• Temporal ambiguity
• Selection
• History
• Maturation
• Mortality/attrition
• Testing and instrumentation
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Construct Validity
• Concerns inferences from the particular exemplars
of a study to the higher order constructs that they
are intended to represent
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Threats to Construct Validity
• Reactivity to the study situations
• Researcher expectancies
• Novelty effects
• Compensatory effects
• Treatment diffusion
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External Validity
• Concerns inferences about the extent to which
relationships observed in a study hold true over
variations in people, conditions, and setting as well
as over variations in treatments and outcomes
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Threats to External Validity
• Interaction between relationship and people
• Interaction between causal effects and treatment
variation
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Trade-Offs and Priorities in Study Validity
• Internal and external validity
• Prioritization and design decisions
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RE-AIM Framework
• Reach
• Efficacy
• Adoption
• Implementation
• Maintenance
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