Ch 20 - Comparing two proportions

Question 1

For large enough samples (2 treatments with 2 independent samples), the sampling distribution of phat1=phat2 is approximately

Answer 1

Normal.

Question 2

For 2 independent SRSs of sizes n1 and n2 with sample proportions of successes p̂1 and p̂2 respectively, an approximate level C confidence interval for p1 – p2 is

Question 2

Answer 2

Question 3

“Plus four” CI for 2 proportions

Answer 3

Question 4

Answer 4

Question 5

Test of significance for 2 proportions

Answer 5

Question 6

Answer 6

Question 7

Relative Risk Reduction (RRR) indicates

Answer 7

how better off you would be relative to receiving a placebo or control treatment.

Question 8

RRR

Answer 8

Question 9

The Absolute Risk Reduction (ARR) is

Answer 9

the absolute difference in outcome rates between the control and treatment groups

Question 10

The Number Needed to Treat (NNT) is

Answer 10

the number of patients that would need to be treated to prevent one additional negative outcome.

Question 11

___ are better indicators of treatment efficacy than ___

Answer 11

ARR and NNT
then RRR.

Question 12

ARR & NNT

Answer 12