outbreaks, causality

Question 1

cohort inclusion is based on-

Answer 1

exposures

Question 2

case control inclusion is based on-

Answer 2

clinical outcome/disease

Question 3

attack rate vs secondary attack rate

Answer 3

attack rate #ill/#susceptible

secondary attack rate: #ill/# exposed to primary cases

Question 4

Using OR to determine source

Answer 4

using case controls, make a 2x2 table for each possible source then calculate OR, high OR = more likely to have been source

Question 5

simple causality model

Answer 5

cause –> effect

Question 6

linear causality model

Answer 6

cause –> effect 1/Cause2 –> effect 2

Question 7

common cause causality model

Answer 7

cause 1 and cause 2 –> effect

Question 8

common effect causality model

Answer 8

cause –> effect 1 and effect 2

Question 9

what is the only absolutely essential criterion for causality?

Answer 9

temporality

Question 10

temporality

Answer 10

cause must precede effect

Question 11

consistency

Answer 11

same cause always yields same effect

Question 12

strength

Answer 12

size of risk of cause on effect

Question 13

specificity

Answer 13

single cause produces specific effects

Question 14

dose-response relationship

Answer 14

increasing level of exposure to cause will increase risk of effect

Question 15

biologic plausibility

Answer 15

cause and effect relationship agrees with accepted understanding of biologic processes

Question 16

coherence

Answer 16

cause and effect relationship is compatible with current knowledge

Question 17

experiment

Answer 17

cause and effect condition can be altered by appropriate experimental design

Question 18

necessary and sufficient, example

Answer 18

Cause –> effect

Ex: measles virus is both necessary and sufficient to cause measles in susceptible person

Question 19

necessary but not sufficient, example

Answer 19

Cause 1 + other cause –> effect
cause 1 is required, but not enough alone to cause effect
ex: mycobacterium tuberculosis is necessary to cause TB infection, but other host factors are also involved

Question 20

sufficient but not necessary, example

Answer 20

Cause 1 –> effect, cause 2–> effect
other causes yield same effect
Ex: enlarged spleen has many causes

Question 21

neither necessary nor sufficient

Answer 21

cause 1 may or may not be present and effect can still occur