Study Design Fundamentals

Question 1

Selection Bias

Answer 1

Error in the selection of/sampling of individuals for a clinical study

Question 2

Observational or Information Bias

Answer 2

Error in the recording of individual factors of a study (e.g inaccurate recording of blood sample timing)

Question 3

Interviewer Bias

Answer 3

Interviews not conducted in a uniform manner

Question 4

Misclassification Bias

Answer 4

variables are misclassified. Nondifferential if all groups have the same rate of misclassification; Differential if there are different rates

Question 5

RR

Answer 5

Relative Risk = A/(A+B)/C/C+D)

Question 6

OR

Answer 6

Odds Ratio = A/C/B/D or (AxD)/(BxC)

Question 7

Sensitivity

Answer 7

Proportion of True Positives correctly identified

Question 8

Sensitivity

Answer 8

• Proportion of True Positives correctly identified

- TP/(TP+FN)

Question 9

Specificity

Answer 9

• Proportion of True Negatives correctly identified

- TN/(TN+FP)

Question 10

PPV

Answer 10

• Proportion of patients with positive test who actually have the disease
• TP/(TP+FP)

Question 11

NPV

Answer 11

• Proportion of patients with a negative test who actually do NOT have the disease
• TN/(TN+FN)