General Methodological Concepts of Research Flashcards
What is the difference b/w quantitative and qualitative studies? Which one is most common?
Quantitative = numbers represent data (can convert words to #s) - most common Qualitative = words used to represent data (don’t convert to #s)
What is the primary difference b/w observational and interventional study designs?
-Interventional = forced allocation to study groups (we intervene and put them in a group) -Observational = no forced allocation to study groups (natural selection)
What study design is considered “experimental?”
Interventional - trying to answer a research Q with a study - IS researcher-forced group allocation; usually accomplished by randomization
What study design is considered “natural?”
Observational -researchers observe subject elements occurring naturally or freely - most not able to prove causation -NO researcher forced group allocation
Which study, interventional or observation, can prove causation? Which would be at the top of the research evidence pyramid?
-Interventional and interventional
Interventional studies include:
Phase 0-4, w/ increasing strength of evidence (so phase 4 has most strength of evidence)
Observational studies include:
-Case reports/series -ecological (not impt) -cross-sectional -case control -cohort (so highest strength of evidence) increasing strength of evidence going down this group
What is the biggest determinant in selecting/developing an effective study design?
The research question
What is the selection of study design and methods based on?
-research Q -forced allocation (randomization) or not -ethics -cost -efficiency/practibility -internal validity -applicability (external validity, generalizability)
Population definition
All ppl making up a common group; from which a sample (smaller set) can be obtained if desired
Study population
the final group of ppl selected for a study
Sample definition
a subset or portion of the full complete population “representatives” of dz state -useful when studying the complete population is not feasible
Inclusion & exclusion criteria are used for what type of study? (when selecting study popln)
Interventional studies
Case and Control OR Exposed and Nonexposed critera are used for which type of study? (when selecting study popln)
Observational studies
What is a null hypothesis? Do researchers want to prove the null hypothesis right or wrong?
-There is no (true) difference between the groups being compared -researchers want to prove the null wrong (so they either reject or don’t reject this perspective) ex) Is two drugs better than one? Null = Two drugs are not better than one
What are the 3 other statistical perspectives or outcomes?
-Superiority = better (common/classic) -Non-inferiority = worse than hypothesis - Equivalency= equal to hypothesis (not talking about null hypothesis here)
In which study is the outcome already known?
Retrospective -goal in assessing past Hx of some activity (exposure/tx)
Which study, prospective or retrospective, is used by all interventional studies?
prospective studies
Probability sample:
every element in the popln has a known (non-zero) probability of being included in sample -most common -equal probability = same chance
Examples of probability sampling schemes
1) Simple Random sampling
- assign random #s–>take randomly selected #s to get desired sample size
- like flipping a coin
2) Stratified sampling
- stratify sampling frame by desired characteristics–>use simple random sampling to select
- make sure the characteristics are balanced (ex- same amount of males and females)
3) Multi-stage random sampling
- uses simple random sampling at multiple-stages towards pt selection
- regions/counties–>city blocks
What category of sampling schemes do ‘Qausi-Systematic’ or ‘Convenience’ belong to?
Nonprobability sampling schemes -decide on what fraction of popln is to be sampled and how they will be sampled -there is a method, but not probabilistic - ex) All ppl who attend clinic on M/W/F
What type of bias may be introduced when using non probabilistic sampling schemes?
Selection bias - bc there is some known/unknown order to the sample generated by the selected scheme
What is internal validity?
Methods Inside the study - is this the best way to assess an outcome? - scientifically rigorous and standardized -accurate and reproducible -clinically applicable
What is equipoise? Whats its use in terms of the use of placebo therapy?
-Genuine confidence that an intervention is worthwhile in order to use it in humans (risk vs benefit) -Some don’t agree with use of placebo if a tx is available, bc they think having ppl use the placebo is putting them at more risk than the ppl receiving tx *** If researcher knows one tx is superior to another, the researcher has to give the better tx**
What are the 4 principles of bioethics
1) Autonomy = self-rule, self-determination; participants must DECIDE FOR ONES-SELF w/o outside influence 2) Beneficence = benefit the individual pt (not society) 3) Justice = equal and fair tx regardless of pt characteristics 4) Nonmaleficence = do no harm (cannot withhold info, provide false info)
_______ issued by National Commission for Protection of Human subjects of biomedical and behavioral research (1978). What are the 3 principles?
Belmont report -Respect for persons – Autonomy (participation should be voluntary) -Beneficence (risks justified by pot. benefits) -Justice (risk and benefits are equally distributed)
Consent?
Agreement to participate based on being fully and completely informed (given by mentally-capable individuals of LEGAl consenting age)
Assent?
Agreement to participate based on being fully informed, given by ppl NOT able to give legal consent -Children or adults not capable of giving consent requires the consent of the parent or legal guardian and the assent of the potential study subject
Who determines the ethical conduct of research? Who holds ultimate decision on level of protocol review?
-IRB = Institutional review board -IRB
Which group reviews before human subject studies start? Which group reviews study data as the study is in progress?
-IRB (b4) -DSMB (as it is progressing)
What does the IRB do?
Performs the ethical determination ***“Ethics Committee” -ROLE = protect human subjects from undue risk - ALL human studies need to be IRB approved before starting -regulated by Federal statues - verify if the 4 principles of bioethics have been met b4 the study starts
What are the levels of IRB review and their differences?
-Full board = all interventional trials with more than minimal risk to patients (high risk to its patients)(drug/product/device approval)
-Expedited = minimal-moderate risk; with or w/o pt identifiers (still looked at but the paperwork is not as heavy and board can get though it more quickly)
-Exempt = low/no risk, no pt identifiers, de-identified dataset analysis, use of existing data/specimens (samples/medical records already there)
What does DSMB do?
Data Safety and Monitoring Board
- review study data as study progresses, assessing for undue risk or benefit b/w groups
- has p_re-determined time intervals for evaluation_
- can stop study early for either overly-(+) or overly-(-) findings in one or more groups
