Incidence and Prevalence

Question 1

What are the 2 measures of dis-ease occurrence?

Answer 1

1. incidence
2. prevalence

Question 2

What is incidence?

Answer 2

no. of dis-ease events that occur over period of time?

Question 3

Incidence exposure equation

Answer 3

EGO = a / EG (/T)

Question 4

Incidence comparison equation

Answer 4

CGO = b / CG (/T)

Question 5

What is prevalence measure?

Answer 5

no. of people with dis-ease at one point in time
(T=1)

Question 6

Prevalence exposure equation

Answer 6

EGO = (a / EG) / 1

Question 7

Prevalence comparison equation

Answer 7

CGO = (b / CG) / 1

Question 8

Is time a required factor for incidence or prevalence measures?

Answer 8

Incidence measures

Question 9

no dis-ease > having dis-ease

Answer 9

occurence/event

Question 10

Incidence or prevalence when easy to observe when dis-ease occurs

Answer 10

measure incidence
- (death, road crash)

Question 11

Incidence or prevalence if hard to observe dis-ease occurrence

Answer 11

measure prevalence
- (obesity, diabetes, psych disease)

Question 12

What incidence rain drops represent?

Answer 12

rain drop = person having dis-ease event during specified time period

Question 13

When do you count how much is in the ‘prevalence pool’

Answer 13

incidence drizzle
- too difficult to measure individual data

Question 14

What is numerical data described in?

Answer 14

numbers
- ie: heart rate

Question 15

What is categorical data described in?

Answer 15

categories (yes/no)
- ie: death

Question 16

What involves counting categorical (yes/no) dis-ease EVENTS?

Answer 16

Incidence
- ONLY categorical outcomes

Question 17

What involves counting categorical dis-ease EVENTS or measuring numerical dis-ease STATES?

Answer 17

Prevalence
- both categorical or numerical

Question 18

Cross-section study

Answer 18

Exposure(s) and outcome measured at one point in time

Question 19

Is a cross-section study incidence or prevalence?

Answer 19

Prevalence

Question 20

How to measure incidence/prevalence in cohort study?

Answer 20

• any point during study
• at beginning

Question 21

Cohort vs cross-section study?

Answer 21

identical structure…
- Cohort = exposures measured longitudinally
- Cross = exposures/outcomes measured at same time

Question 22

What determines dis-ease incidence?

Answer 22

numerator = no. of rain drops falling over period of time
Incidence depends only on no. of events that fall during specified time period.

Question 23

What determines dis-ease prevalence?

Answer 23

numerator = amount of dis-ease in prevalence pool at point in time
prevalence = how much drizzle (incidence) in pool AND leakage (death) or evaporate (cured)