Lecture bioinformatic databases - Thursday
16 important questions on Lecture bioinformatic databases - Thursday
What are other names for follow up studies?
The aim of the follow up / cohort study is ...
--> estimate association between exposure and outcome
What are exapmles of outcome in a study?
- Higher grades + faster learning
- Never study anything twice
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What are examples of exposure in studies?
How do you indentificate exposure groups?
2. Selection by researcher (rare risk factors) = not common
--> researcher search for people in exposure group
3. Selection by chance
What is the difference between an observational and experimental follow up study?
Observational - exposure is fixed, determined by participants or circumstances
What are the pros and cons of prospective studies?
Con: time-consuming / expensive
What are two types of study populations?
What is the difference between closed and open/dynamic cohorts?
Dynamic: losses and replacements, same number of people (dynamic stationary population)
How do you calculate the cumulative incidence?
2. Via life table (Kaplan-Meier) - takes unequal follow up duration into account
3. From incidence rate - linear approximation / exponential approach
What is the cause of unequal lenghts of follow up?
2. Unequal starting times
3. Withdrawn alive
-> solved by Kaplan Meier method
What is the difference between withdrawn alive and lost to follow up (LtFU)?
Loss to follow up = dependent on outcome, probably due to sickness or recovery -> influences study
How do you calculate the rate ratio and risk ratio for the absolute risk?
Risk = ci / Ni
How do you calculate the absoulte rate difference?
How do you calculate relative risk (RR)?
-> Ra = absolute risk group A (exposed)
-> Rb = absolute risk group B (not exposed)
How do you calculate the relative risk reduction (RRR)?
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