Module 5

Question 1

What will happen if the cutoff for positive cases is high?

Answer 1

If the cutoff for positive cases is high, the test will eliminate more cases of false positives but will produce more false negatives.

Question 2

What happen if the cutoff for positive cases is low?

Answer 2

If the cutoff for positivity cases is low, the test will eliminate more false negatives but produce more false positives.

Question 3

What does reliability in a test mean?

Answer 3

Reliability is the ability of the test to give the same result (for whatever the threshold is) on repeated testing.

Question 4

Reliability and validity are example of what?

Answer 4

Characteristics of a screening test

Question 5

What does validity mean in a test?

Answer 5

Validity is the ability of a test to successfully identify people with disease as positive cases and people who are negative for disease as negative cases.

Question 6

what are 2 measurements of validity?

Answer 6

sensitivity and specificity

Question 7

what is the definition of sensitivity?

Answer 7

Sensitivity is the probability that a test correctly identifies people with preclinical disease as positive

Question 8

what is the definition of specificity?

Answer 8

Specificity is the probability that a test correctly identifies people without preclinical disease as negative

Question 9

What is the formula for sensitivity?

Answer 9

Sensitivity = people with preclinical disease test positive/people with preclinical disease X 100

express as a percentage

Question 10

What is the formula for sensitivity when looking at a 2x2 table?

Answer 10

TP / (TP + FN) x100

Question 11

What is the formula for specificity?

Answer 11

Specificity = people without preclinical disease test negative/people without preclinical disease x 100

express as an percentage

Question 12

What is the formula for specificity when looking at a 2x2 table?

Answer 12

TN / (TN + FP) x 100

Question 13

What is the best way to measure the feasiblity of a test?

Answer 13

Predictive Value

Question 14

What are the 2 parts of Predictive Value?

Answer 14

Predictive Value Positive and Predictive Value Negative

Question 15

What is the predictive value positive (PVP)?

Answer 15

Predictive Value Positive (PVP) is the proportion of people who test positive who have preclinical disease

Question 16

What is the predictive value negative?

Answer 16

Predictive Value Negative (PVN) is the proportion of people who test negative who do not have preclinical disease.

Question 17

What is the formula for Predictive Value Positive (PVP)?

Answer 17

PVP = people with preclinical disease test positive/people who test positive X 100

Question 18

What is the formula for Predictive Value Negative (PVN)?

Answer 18

PVN = people without preclinical disease test negative/people who test negative x 100

Question 19

What is the formula for PVP when looking at a 2x2 table?

Answer 19

PVP = TP / (TP/FP) x 100

Question 20

What is the formula for PVN when looking at a 2x2 table?

Answer 20

PVN = TN / (TN + FN) x 100

Question 21

A …. PVP is needed for a successful screening program

a) low
b) high

Answer 21

A high PVP is needed for a successful screening program

Question 22

What influences the Predictive Value Positive the most? Why?

Answer 22

Specificity influences it the most because it controls the number of false positives.

Question 23

Sensivity and … also influence the PVP.

Answer 23

Prevalence of DPCP (detectable preclinical phase)

this basically means the prevalence of the disease in its preclinical stage

Question 24

explain what primary prevention is and who it is aimed at

Answer 24

Primary Prevention tries to prevent people from getting the disease and it is for people who do not have disease

Question 24

explain what primary prevention is and who it is aimed at

Answer 24

Primary Prevention tries to prevent people from getting the disease and it is for people who do not have disease

Question 25

explain what secondary prevention is and who it is aimed at

Answer 25

Secondary prevention is trying to reduce severity of disease and delay onset of symptoms and it is for preclinical cases of disease (not yet symptomatic)

Question 26

what is tertiary prevention and who is it aimed at?

Answer 26

Tertiary prevention is trying to reduce slow progression of disease/improve quality of lifeand it is for clinical cases of disease (has symptoms)

Question 27

When the does preclinical phase start/end? When does the clinical phase start/end?

Answer 27

Preclinical phase is from the biological start of disease until symptoms show. Clinical phase is from the time symptoms of the disease first show until the disease is cured or the person dies.

Question 28

Put these stages of history of a disease in order
- Pathological onset
- Relapse
- Death
- Clinical symptoms
- Remission

Answer 28

• Pathological onset
• Clinical symptoms
• Remission
• Relapse
• Death