renter

Question 1

what are the 4 diagnostic strategies?

Answer 1

1. pattern recognition
2. method of algorithm
3. method of exhaustion
4. hypothetico-deductive method

Question 2

what is a test?

Answer 2

any device or process used to detect or elicit a sign, substance, tissue, change or response

Question 3

diagnostic test

Answer 3

application for a test to clinically ill individuals in order to assess disease status

Question 4

screening test

Answer 4

application of a test to apparently healthy individuals to detect infection, exposure or subclinical disease

Question 5

define accurate

Answer 5

both valid and reliable

Question 6

define reliability

Answer 6

will give the same results if administered more than once to same patient

Question 7

define valid

Answer 7

correctly identifies the true status of the animal (identifies what you want to identify)

Question 8

false positive test

Answer 8

tests positive for disease but the animal is healthy

Question 9

false negative test

Answer 9

tests negative for disease but the animal has the disease

Question 10

define sensitivity

Answer 10

-ability of the test to detect disease
-diseased animals test positive
A/(A+C)

Question 11

define specificity

Answer 11

-ability of the test to detect non diseased
-healthy animals that test negative
D/(B+D)

Question 12

when the sensitivity is high, a negative test:

Answer 12

rules out the disease

Question 13

when the specificity is high, a positive test:

Answer 13

confirms the disease

Question 14

we would want to max out our ability to rule out disease by maximizing:

Answer 14

sensitivity

Question 15

we would want to maximize our ability to diagnose disease by maximizing:

Answer 15

specificity

Question 16

what is true prevalence?

Answer 16

-proportion or percentage of the total population that are truly diseased (N)

Apparent prevalence- (1-sp)/
1-[ (1-sp) + (1-sn) ]

Question 17

apparent prevalence

Answer 17

proportion or percentage of the total population that test POSITIVE

Question 18

positive predictive value

Answer 18

proportion of test-positives that are infected/diseased

Question 19

negative predictive value

Answer 19

proportion of test-negatives that are free of disease

Question 20

expected prevalence

Answer 20

pre-test probability

-(probability the patient has disease prior to next test)

Question 21

predictive value

Answer 21

post-test probabililty

Question 22

define cut point

Answer 22

it defines positive or negative results, used for continuous values

Question 23

True/False: concerning specificity and sensitivity, you often have to sacrifice one to get the other.

Answer 23

true

Question 24

low cut points make a lot more people test:

Answer 24

positive

Question 25

high cut points make a lot more people test:

Answer 25

negative

Question 26

What is the ROC curve?

Answer 26

graphical approach to choosing a cut point

Question 27

What happens with a TG-ROC curve?

Answer 27

the cut point is where two lines cross

Question 28

define reference range

Answer 28

the set values 95% of the normal population falls within

-(that is, 95% prediction interval)

Question 29

what does sequential testing improve?

Answer 29

post-test probability

-followup testing only on just the positive or negative animals

Question 30

what is surveillance?

Answer 30

continuous and systematic process of collection, analysis and interpretation of data and dissemination of info on disease occurence in a population to initiate control measures or further investigation

Question 31

what is monitoring?

Answer 31

routine observation and analysis of measurements

Question 32

if threshold is lowered, you increase what?

Answer 32

sensitivity

Question 33

what is passive surveillance?

Answer 33

collects voluntary data

Question 34

what active surveillance?

Answer 34

data solicited or actively collected

Question 35

fewer false negatives =

Answer 35

higher sensitivity

Question 36

fewer false positives =

Answer 36

higher specificity

Question 37

lower cut-point =

Answer 37

no false negatives (100% sensitivity, 100% NPV)

Question 38

higher cut-point =

Answer 38

no false positives (100% specificity, 100% PPV)

Question 39

in an ROC curve, a dot where on the curve optimizes both Sn and Sp?

Answer 39

top left corner

Question 40

on a TG-ROC curve, a dot where on the graph optimizes Sn and Sp?

Answer 40

where the lines intersect

Question 41

____ increases as prevalence or pre-test probability of dz increases

Answer 41

PPV

Question 42

what are the Sn and Sp of the answers to your questions that you ask the owner?

Answer 42

90% Sn and 60% Sp

Question 43

summary of tests in series:

Answer 43

• all tests positive = positive
• increases Sp and PPV
• decreases Sn and NPV

Question 44

summary of tests in parallel:

Answer 44

• one or more tests positive = positive
• increases Sn and NPV
• decreases Sp and PPV