Sensitive/specificity/PPV/NPV/incidence/prevelance

Question 0

Sensitivity is also called

Answer 0

True positive rate

Question 1

Fixed properties of a test

Answer 1

1. Sensitivity

2. Specificity

Question 2

Evaluation of a diagnostic test

Answer 2

Uses 2X2 table comparing test results with te actual presence of disease (vertical: TEST: + - / horizontal: disease: + -)

Question 3

Sensitivity equation

Answer 3

TP/(TP+FN)=1-FN rate

Question 4

Sensitivity - definition

Answer 4

Proportion of all people with disease who test positive or,

The probability that a test detects disease when disease is present

Question 5

Value approaching 100% sensitivity is desirable for ruling …. disease
It indicates

Answer 5

OUT

A low false negative rate

Question 6

High sensitivity test used for screening in disease with ….. prevalence

Answer 6

LOW

Question 7

Specificity is also called

Answer 7

TN rate

Question 8

Specificity

Answer 8

Proportion of people without disease who test negative
or,
The probability that a test indicates non disease when disease is absent

Question 9

Value approaching 100% specificity is desirable for ruling …. disease
and indicates a

Answer 9

IN

Low false positive rate

Question 10

High specificity test used for

Answer 10

Confirmation after a positive screening test

Question 12

Positive predictive value

Answer 12

1. Proportion positive test that are true postive

2. Probability that person actually has the disease given a positive test result

Question 12

Positive predictive value equation

Answer 12

TP/(TP+FP)

Question 13

PPV varies directly with

Answer 13

Prevalence or pretest probability

High pretest –> high PPV

Question 14

Negative predictive value

Answer 14

1. Proportion of negative test results that are true negative
2. Probability that person actually is disease free given negative test result

Question 15

Negative predictive value equation

Answer 15

TN/(FN+TN)

Question 16

NPV varies inversely with

Answer 16

1. Prevalence
2. Pretest probability
   High pretest probability –> low NPV

Question 17

Prevalence

Answer 17

Number of existing cases/number of people at risk

At a point in time

Question 18

Incidence rate

Answer 18

(Number of new cases in a specified time of period)/(population at risk during same time)

Question 19

Prevalence directly reversible

Answer 19

1. Incidence

2. Average disease dutation

Question 20

Incidence and prevalence in common cold. Bigger?

Answer 20

Very similar because duration is short

Question 21

Incidence and prevalence in chronic diseases. Bigger?

Answer 21

Prevalence. Long duration

Question 22

Posspitive and negative predictive value vary depending on

Answer 22

Disease prevalence

Question 23

Specificity equation

Answer 23

TN=TN/TN+FP

= 1-FP

Question 25

High sensitivity test used for

Answer 25

SCREENING in diseases with LOW prevalence

Question 26

town population is 7.500. In 2011, 200 residents diagnosed with RA. in 2012, 100 more residents are discovered by RA. incidence, prevalence?

Answer 26

incidence = 100/7300
prevelance = 300/7500

Question 27

fixed properties of a test and properties that vary

Answer 27

fixed: specificity, sensitivity
vary: PPV, NPV (depending on disease prevalence)

Question 28

association between PPV, NPV, sensitivity, specificity

Answer 28

high sensitivity –> high NPV

high specificity –> high PPV