Purpose of Analytical Studies?
- ID & explain the cause of dz
- numerically assess risk factors
3 parts of an Analytical Study?
- Data collection
- Data analysis
- Data interpretation
Study type that compares dz occurrence between "exposed" & "non-exposed"
2 Strengths of Cohort Studies
- Rare exposure
- can examine multiple outcomes of a single exposure
Weaknesses of Cohort Study
- Not good for rare dz.
- time consuming if there is a long period between exposure & dz.
Prospective Cohort follows groups from _______ to ________.
present to future
Strengths of Prospective Cohorts
- measure Incidence
- describes temporal relationships
- collect data on possible confounders
Weaknesses of Prospective Cohorts?
- Expensive & long
- Lack of follow-up can affect validity
- Requires a large # of subjects
Retrospective Cohort follows subjects from _______ to _______.
present to past
Strengths of Retrospective Cohorts
- data is already present
- easy to perform
Weaknesses of Retrospective Cohorts
- Need good records → confounders
- Selection bias
Relative Risk looks at what?
how many times more/less likely exposed individuals are to get the dz. relative to non-exposed individuals
How do you calculate RR?
Purpose of Cofidence Interval (CI)?
allows you to determine whether or not the RR/OR can be deemed statistically significant
When is the result said to be statistically significant?
(in regards to the CI)
- if the CI falls entirely on either side of the null value (1.0)
- has be 95% or higher
_______ are study subjects who have the disease of interest in Case-Control Studies.
What is the purpose of Case-Control Studies?
compare frequency of exposure factors in cases w/ dz and cases w/o dz.
_______ are subjects who are dz free at the time of selection in Case-Control Studies.
Where does Case Selection come from?
- all cases in a defined population or from the general population
- often more convient
Controls selected from CCS should be __________ to cases in every respect except _______.
How do you calculate Odds Ratio (OR)?
Which study uses OR?
4 Strengths of Case-Control Study?
- Rare dz.
- Multiple exposure
- cheap & fast
- Small # of subjects
4 Weaknesses of Case-Control Studies?
- No Incidence or Prevalence
- Bias→ recall, selection, information, misclassification
- Difficult to establish temporal relationships
Objective of Randomized Clinical Trials (RCTs)?
subjects followed over time to test possible effects of therapeutic & preventative interventions
Which RCT evaluates whether agent/procedure reduces risk of dz. developing in those currently free from dz?
3 Strengths of RCTs?
- Control over study situation
- Casual relatioship can be established
- Reduced confounding & bias
5 Weaknesses of RCTs?
- May not accurately represent normal population
- Need large sample size → $$
- May be timely
- Ethical issues
- Bias if no blinding is present
Test that is:
- Applied to animals showing CS of dz.
- Confirms or classifies dz. status
This test is used to:
- to ID undiagnosed cases of dz in apparently healthy populations