Study Designs And Methods Flashcards
What is the hallmark feature difference of interventional studies and observational studies?
Interventional, you force subjects to do something or you force the allocation of the subjects into groups.
What are the 5 interventional studies in order of increasing strength of evidence?
What are the 3 observational studies in order of increasing evidence?
Phase 0-4
Cross sectional, case control and cohort
What is the correct way to ask our question for whatever study we are doing?
What are the 3 statistical perspectives that can be taken in interventional studies?
Null hypothesis, there is no difference between the groups being compared
Superiority, neoninferiotry (its not worse), or equivalent
Explain the gist of a prospective, retrospective, and ambidirectional studies?
Prospective: outcome is not yet known when we start the study
Retrospective: outcome is already known
Ambidirectional: first look retrospectively and then look prospective. Follow those people we know with an outcome and see if there are additional outcomes or occurrences.
Which types of study designs are prospective?
Phase 0-4 and cohort
Explain internal validity and external validity?
Internal validity: validity of everything inside the study, how it was done, how everything was obtained, etc.
External validity: are you able to apply the study of the sample to the population.
For observational studies, we focus on how the groups were organized to tell which type of observational study? What type fo study comes to mind for the following groups? By disease? By exposure? Together due to a common factor? Data collected across large pop?
Case control/ nested case control
Cohort
Cohort
Cross sectional
Explain what a case control study is?
We randomly select a certain number of people who have the disease/outcome we want to study and a number of people who do not have it and put them in separate groups. We then see if there are any differences of those who have the outcome and then further break the case and control group into yes they have the difference and no. This commonly generates an odds of exposure for each, then an odds ratio as the measure of association.
Case control studies are great for what types of diseases and what fashion are these babies usually carried out in?
Rare disease
Retrospective fashion
5 strengths of case control study designs?
What is a nested case control study design?
Good for rare diseases, determining associations, you can evaluate multiple exposures for one outcome, diseases that take a long time to come on, good when ethical issues limit interventional studies.
A case control study derived from, occurring within or after a prospective study.
What is the defining feature of a cohort study?
What are the two types of cohort and explain?
The first you do is group together people that have something in common and then allocate them into groups based on whatever.
Study group allocation: based on exposure status first and then check outcome
Group definition: a group with something in common. Essentially the normal cohort study.
What do cohort studies commonly generate?
Cohort studies are useful in studying what type of exposure?
Cohort studies can be conducted in what type of fashion?
Risk of disease/outcome for each then a risk ratio/relative risk as a measure of association
Rare exposure
Retrospective or prospective
2 strengths to remember about cohort studies?
Evaluate multiple outcomes from one exposure
Able to represent temporality, which is the closes thing to causation in observational studies
How do we best define/explain a cross sectional study?
This is taking a snap shot in time of a large population, nation, regardless of exposure or outcome. It’s a prevalence study of everything in a population at a moment in time and then do with it what you want.
