Lecture 4 Flashcards
What is the objective of Case-Control?
To find possible predictors of outcomes
What are the overall steps for case control?
- cases from a specified population are sampled
- controls are sampled
- the 2 groups (case vs control) are retroactively compared
- calculate odds ratio
Can cases and controls come from different populations?
absolutely not! They must be as similar as possible
What’s a good study method to to study a uncommon condition? DOUBLE CHECK
Case-control case! It allows us to maximize the effort and finances gone to recruit and find people from this small population
What are the limitations of case control studies?
More vulnerable to biases, Can’t consider more than one disease, not feasible for rare exposures
What biases in particular affect case control studies?
- Sampling bias (unrepresentative samples) 2. Recall bias (retroactive and based on recall)
How can sampling bias be solved?
random sampling
How can recall bias be solved?
recorded data`
What is the objective of a RCT?
To observe treatment effect
What is the definition of a RCT?
Quantitative, comparative, and controlled experiments in which a group of a investigators studies two or more interventions by administering them to groups of individuals who have been randomly assigned to recieve each intervention.
What’s a good alternative to having a control group with no treatment at all?
control could have generic/current treatment vs new treatment. there should be a difference
Why are we so worried about confounding variables?
We might not be able to correctly see the pattern that leads from variable of interest to affect. Other things could influence our data!
Define blinding
Being unaware of the condition in which a participant is assigned
What are the types of RCTs by binding?
- not blinded: both researchers and participants are aware of the group they are a part of
- Single-binding: only patient is unaware of the group
- Double blinding: both the treating physician and participant is in the intervention or the control condition
- Triple blinding: participants, treating physicians, and the trial investigator are all blinded (via coded values so even statistician is )
List the Types of RCT by phase with brief description
Phase 1: is it safe? (tested on willing human volunteers)
Phase 2: does it work?
Phase 3: how well does it work?
Phase 4: is there any adverse affects that we could have missed?
Limitations of RCT?
May not be ethical, or feasible. Recall bias again (when collecting history for ex), small number of participants can be inaccurate
What are hill’s criteria of causality?
- Strength (strong association) 2. Consistency (same result across different studies and situations) 3. Specificity (very specific association and effect) 4. Temporality (effect has to occur after the cause) 5. Biological gradient (greater exposure should lead to greater effect) 6. Plausibility (consistent with current body of knowledge) 7. Coherence (epidemiological findings and lab findings agree)
What are the 3 types of observational studies?
Cohort, Prevalence, and Case control
How is the defined population split up in a case-control study?
First disease (cases) and not diseased (controls) are split, then those two categories each are split into those exposed/not exposed.
What are case control studies useful for?
- studying uncommon conditions (lots of useful information with limited participants)
- generating a hypothesis for further studies
- Require less resources and less time consuming
What is the main strength of RCTs?
randomizing subjects means that on average all other possible causes are equal between the two groups
