Study Designs

Question 1

Internal validity

Answer 1

Does the study address bias, confounding, etc? Is the study design adequate?

Question 2

External validity

Answer 2

Can the results be replicated or applied to other groups/patients?

Question 3

Incidence

Answer 3

Probability of developing a disease

Question 4

Prevalence

Answer 4

Measures current cases at point in time

Question 5

Relative Risk vs Odds Ratio

Answer 5

Relative risk - risk of disease in exposed/non exposed group

Odds ratio - odds of exposure in disease or non disease group

If CI contains 1 in either, then no stat difference.
If the RR/OR is less than 1 - negative association (risk is lower) and is more than 1, positive association

Question 6

NNT

Answer 6

Number needed to treat

NNT = 1/ARR

Question 7

Sensitivity

Answer 7

proportion of true positives

Negatives can rule out disease

Question 8

Specificity

Answer 8

Positives can rule out a disease

Proportion of true negatives identified by a test