Confidence intervals for risk ratio and odds ratio

Question 1

Risk ratio ranges

Answer 1

• RR ranges from 0 to infinity, can’t be less than 0
• RR< 1 exposure is protective (e.g., vaccine, healthy diet)
• RR=1 exposure has no effect
• RR> 1 exposure is positively associated with disease
• BUT singal number not tell if RR/OR significantly different from RR=1
  e. g. rr= 1.5 might represent sig increased risk or not
• can tell through confidence intervals

Question 2

Confidence intervals (def)

Answer 2

= range of values thats likely to include a population value with certain degree of confidence (usually 95%)

Question 3

Rule for confidence intervals

Answer 3

• null hypothesis = rr=1 exposure has no effect
• if CI contains 1 = rr not sig diff from 1 = exposure not significant
• if CI doesnt contain 1 = rr is sig diff from 1 = exposure is sig associated with outcome
  e. g. 0.98 to 1.9 contains 1