Estimating Risk I & II

Question 1

Relative Risk // Rate Ratio

Answer 1

• the STRENGTH of the relationship between exposure and outcome
• the probability of an outcome for exposed group and unexposed group

Question 2

When the relative risk (rr) is 1.0

Answer 2

• no difference between the exposed and unexposed groups

Question 3

when the relative risk (rr) is > 1

Answer 3

• the exposure “increases” risk – it’s possibly a risk factor

Question 4

when the relative risk (rr) is < 1

Answer 4

• the exposure variable “decreases” risk – it’s possibly a protective factor

Question 5

Risk Difference

Answer 5

• that is the excess risk than can be attributed to having had the exposure

Question 6

Odds Ratio

Answer 6

• the ratio of the probability of occurrence of an event to that of non-occurrence
• tells us how much higher the odds of exposure are among case-patients than among controls

Question 7

What kinds of studies can odds ratio be used for?

Answer 7

• cohort
• cross-sectional
• case-control

Question 8

What kinds of studies can relative risk be used for?

Answer 8

• only cohort studies

Question 9

When odds ratio is < 1.0

Answer 9

• cases are less likely to be exposed than controls

- protective factor

Question 10

When odds ratio equals 1.0

Answer 10

• odds of exposure are the same in the cases and controls,

- exposure has no influence whatsoever on the disease outcome

Question 11

When odds ratio is > 1.0

Answer 11

• cases are more likely to be exposed than the controls

- risk factor

Question 12

Point Estimate

Confidence Intervals

Answer 12

• “best guess” number based on analysis of the data

- CI = data around the calculated odds ratio

Question 13

Statistical Significance

Answer 13

• is determined using statistical tests such as the Х2 (chi-square) test.

Question 14

P-value

Answer 14

• the probability that a finding could have occurred by chance alone – of less than 0.05

Question 15

Sample size influence confidence intervals by…

Answer 15

• yielding narrower confidence intervals to reveal statistically significant associations

Question 16

Attributable Risk

Answer 16

• tells how much of the health burden due to a specific disease can be alleviated through the elimination of a risk factor for that disease
• tells us the potential for prevention

Question 17

Target Population

Answer 17

• those most susceptible to the illness

Question 18

Etiologic fraction

Answer 18

• attributable risk in the exposed, in the hope that the excess risk characterized by that number will MOTIVATE BEHAVIOURAL CHANGES.

Question 19

Population Attributable Risk (PAR) = Population Etiologic Fraction

Answer 19

• the benefit of investing in things like prevention should be HIGH for the entire population for it to command political attention

Question 20

Absolute Risk

Answer 20

• the incidence of a disease in a population

- is implicit, but doesn’t tell us any associations of risk

Question 21

Rarity Assumption

Answer 21

• when the disease being studied does not occur frequently