Statistics

Question 1

Definition of validity?

Answer 1

Degree to which data measure what they were intended to measure

Question 2

Equation for sensitivity?

Answer 2

Sen = TP / (TP+FN)

Question 3

Equation for specificity?

Answer 3

Spec = TN / (TN+FP)

Question 4

Definition of sensitivity?

Answer 4

What percentage of people with disease have a positive test?

Question 5

Definition of specificity?

Answer 5

What percentage of people without disease have a negative test?

Question 6

Definition of positive predictive value?

Answer 6

what percentage of people with a positive test actually have the disease?

Question 7

Equation for positive predictive value?

Answer 7

PPV = TP / (TP+FP)

Question 8

Definition of negative predictive value?

Answer 8

what percentage of people with a negative test are actually free of disease?

Question 9

Equation for negative predictive value?

Answer 9

TN / (TN+FN)

Question 10

Equation for RR (Risk Ratio / Relative Risk)?

Answer 10

Risk in treatment group / risk in placebo group

Question 11

Equation for relative risk reduction?

Answer 11

1 - relative risk —or— 1 - risk ratio

Question 12

Relation between odds ratio & relative risk?

Answer 12

If frequency is low, they are similar. If frequency is high, then OR is inflated compared to RR

Question 13

Equation for odds ratio?

Answer 13

OR = (A/B)/(C/D)

Question 14

Definition of odds ratio

Answer 14

the odds of a disease occuring in the presence of a treatment versus the odds of it occuring in the absence thereof

Question 15

Equation for absolute risk reduction?

Answer 15

Risk in intervention MINUS risk in control arm

Question 16

Equation for number needed to treat?

Answer 16

NNT = 1 - ARR