⚖️430: Research Methods QUANTITATIVE FINAL Flashcards
What are the major classes of quantitative design?
- Experimental (and Quasi-experimental)
2. Non-experimental
What are the 3 criteria of causality?
- Preceded the effect in time
- Association between the cause and effect
- Relationship cannot be due to the influence of a third variable or confounder
What are the 3 aspects of experimental design?
- Manipulation
- Control/comparison
- Randomization
What are the different experimental designs?
- Randomized controlled trial (POSTTEST ONLY)
- Randomized controlled trial (PRETEST-POSTTEST)
- Cross-Over Design
What is a cross-over experimental design?
Sample:
- Treatment 1 ➡️ washout ➡️ Treatment 2
- Treatment 2 ➡️ washout ➡️ Treatment 1
What is a pretest-posttest randomized controlled trial experimental design?
Measures outcomes before and after experimental and control interventions
What are limitations of experimental designs?
- Not everything can be manipulated
- Hawthorne Effect
- Blinding not always possible
- May be unethical to withhold care
What are quasi-experimental designs?
Involves a manipulation but lacks either randomization or control group
What are the 2 categories of quasi-experimental designs?
- Non-equivalent control group design
(Intervention group compared to nonrandomized control group) - Within-subjects designs
(One group studied before and after intervention)
What are strengths of quasi-experimental designs?
More feasible as compared to a true experiment
What are limitations of quasi-experimental designs?
- More difficult to infer causality
2. Rival explanations for results
What are categories of non-experimental designs?
- Correlational cause-probing research
- Descriptive correlational designs
- Univariate descriptive studies
- Cohort studies
- Case-control study
What is a cohort study?
Investigator identified exposed and none posed groups (cohorts) and follows them forward in time.
- Useful when harmful outcomes occur infrequently
***Exposed and unexposed may begin with different risks of target outcomes (CONFOUNDING)
What are strengths of non-experimental designs?
- Efficient way to collect large amounts of data when intervention/randomization no possible
- Does not require artificial provision of exposure
- Treatments not withheld
What are limitations of non-experimental designs?
- Rival explanations for results
2. Limited ability to infer causality
Cross-sectional
Data collection at one time point, or more than one in close succession
Longitudinal
- Data collected at multiple time points over days/months/years
- Better at showing patterns of changed and at clarifying whether a chase occurred before an effect
- ATTRITION = loss of participants over time
Which is NOT another term for randomization? A. Random sampling B. Random allocation C. Random assignment D. None of the above
A. Random sampling
What are the 4 main aspects of Validity?
- Statistical Conclusion Validity
- Internal Validity
- Construct Validity
- External Validity
Validity
The degree to which inferences made in a study are accurate and well-founded
What are ways of controlling extraneous/confounding variables?
- Constancy of conditions
- Formal protocol to enhance intervention fidelity
- Randomization
- Homogeneity (restricting sample)
- Matching
- Statistical control (ex. Analysis of covariance)
Statistical conclusion validity
The ability to detect true relationships statistically
What are threats to statistical conclusion validity?
- Low statistical power (ex. low sample size)
- Weakly defined “cause” - independent variable poorly constructed
- Low implementation fidelity
- Poor intervention adherence
Internal validity
Extent to which it can be inferred that the independent variable caused or influenced the dependent variable
What are threats to internal validity?
- Temporal ambiguity
- Selection threat - bias arising from preexisting differences between groups
- History - other events co-ocurring with the causal factor
- Maturation - processes that result from passage of time
- Mortality/attrition - differential loss from groups
Construct validity
Key constructs are adequately captured in the study and thus the evidence in a study supports inferences about the constructs that are intended to represent.
What are threats to construct validity?
- Poor construct validity of measurement tools
- Reactivity to the study situation (Hawthorne Effect)
- Researcher expectancies
- Novelty effect
- Compensatory effects
- Treatment diffusion or contamination
External validity
The extent to which it can be inferred that the relationships observed in a study hold true in other samples or settings (ie. generalizability)
What are threats to external validity?
- Sample that is mom-representative of population
- Intervention that is difficult to replicate
- Artificiality of research environment
Open-ended questions
- Allows for more in-depth data
2. Analysis can be difficult and time-consuming
Closed-ended questions
- Greater privacy
2. Less likely to go unanswered
Composite psychosocial scales
Used to make fine quantitative discriminations among people
With different attitudes, perceptions, or needs
Likert Scales
- Consist of several declarative statements (items) expressing viewpoints
- Responses are on ah agree/disagree continuum (usually 5 to 7)
- Responses to items are summed to compute a total scale score (SUMMATED RATING SCALE)
Observation in quantitative studies
- Structured observations of pre-specifies units (ex. Behaviours, actions, events)
- Structures in what to observe, how long, and how to record
Methods:
- Category systems
- Checklists
Bromage Score
Observational rating on a descriptive continuum to test degree of motor block after epidural
What are disadvantages of observations?
- REACTIVITY = Behaviours May be altered by awareness of being observed
- Observer bias
- Resources required to gain entry into setting
In vivo measurements
Performed directly within or on living organisms (ex. Blood pressure)
In vitro measurements
Performed outside the organism’s body (ex. Urinalysis)
What are advantages of biophysical measures?
- Precision
- Objective
- Validity
What are disadvantages of biophysical measures?
- Resources required
- Many factors may affect variability
- Ethical responsibilities
What are the 2 types of biophysical measures?
- In vivo
2. In vitro
Errors of Measurement
Obtained score = True score +/- Error
= Signal +/- Noise
Reliability
The extent to which scores are free from measurement errors.
Reliability is consistency of measure, validity is accuracy of measure.
Reliability coefficients
0.00 to 1.00
Unsatisfactory < 0.70
Desirable >= 0.80
What are the 3 methods of assessing reliability?
- Test-Retest Reliability
- Internal Consistency
- Interrater Reliability