Module 4

Question 1

Sensitivity =

Answer 1

Ability to correctly screen or diagnosis a condition TRUE POSITIVES

Question 2

Specificity

Answer 2

Ability to correctly screen OUT people WITHOUT the condition
TRUE NEGATIVES

Question 3

Sensitivity Calculation

Answer 3

A/(A+C)

A= true positives / everyone with disease (true + & false -)

Question 4

Specificity Equation

Answer 4

D/(B+D)
true negatives divided by everyone who doesn’t have the disease (false - & true -)

Question 5

What would calculation be for sensitivity and specificity

Answer 5

Sensitivity = a/(a+C) 18 / (18+2) = .9 = 90%
Specificity =
d/(b+d) = 76/(4+76) = 76/80 = 0.95 = 95%

Question 6

Cohort Study vs Case-control study

Answer 6

Cohort - real time following of individuals
Case-control = look back at exposure you are testing

Question 7

Cohort study statistic =

Answer 7

relative risk

Question 8

case-control study statistic =

Answer 8

odds ratio

Question 9

Relative risk tells you what

Answer 9

incidence of outcome with exposure
RR=1 same as exposed vs unexposed

> 1 = exposed group higher risk
< 1 = exposed group lower risk

Question 10

RR = 0.80 how would you interpret this

Answer 10

(1-0.8)*100 = 0.2

0.2 * 100 = 20%

20% of subjects

Question 11

RR = 2.38 & 4.46 how do you interpret

Answer 11

4.46 group 4.46 times more likely to acquire what is being tested

Question 12

What does Odds Ratio tell you

Answer 12

how many times more likely the odds of finding an exposure in someone with the disease vs someone without the disease

Question 13

OR = 1
OR >1
OR<1

Answer 13

1 no increase
>1 increased frequency
< 1 decreased frequency of finding disease in the exposed group

Question 14

survival analysis =

Answer 14

method used to examine duration of time until an event occurs

Question 15

Censored Data =

Answer 15

those who don’t have the event during the study or drop out of study

Question 16

Kaplan Meier Curve

Answer 16

nonparametric
X axis time
y axis proportion of sample that have not had the event (could be death or something else that is being measured)

Question 17

TEST “A” RESULTS TEST “B” RESULTS
Confirmed HIV positive Confirmed HIV negative Confirmed HIV positive Confirmed HIV negative
Test A: positive 10 5 Test B: positive 13 3
Test A: negative 2 20Test B: negative 2 17
Calculate sensitivity for test A
calculate specificity for test A

Answer 17

10/(10+2) = 0.83333
20/(5+20) = 0.8

Question 18

TEST “A” RESULTS TEST “B” RESULTS
Confirmed HIV positive Confirmed HIV negative Confirmed HIV positive Confirmed HIV negative
Test A: positive 10 5 Test B: positive 13 3
Test A: negative 2 20 Test B: negative 2 17
Calculate sensitivity for TEst B
Calculate Specificity for Test B

Answer 18

sensitivity 13/(13+2) = 0.8667
specificity 17/(3+17) = 0.85

Question 19

A researcher has developed a new rapid test for covid 19. She evaluates her new test by testing 100 patients with both her rapid test and the gold standard lab test. She calculates her specificity to be 94%. What does this tell you?

Answer 19

The rapid test resulted in a negative result when the person truly did not have covid19 94% of the time (true negatives)