module 2 Flashcards

1
Q

what do we mean when we ask if the diagnostic tests are accurate

A

does the diagnostic test provide sufficient information to reliably distinguish individuals with or without the condition of interest

how much does the probablity change pre and post test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

are diagnostic clinical test ever 100% accurate

A

no

  • there is alway a chance of false negatives and positives
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what does sensitivity address

A

how good in the test ID people with the disease

snOUT - rule out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does specificity addres

A

how good is the test at ID without the disease

spIN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does the positive predictor rule address

A

if a person test positive - what is the probability that they have the condition

ID those who have the disease amongst those who tested positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does the negative predictor rule address

A

if a person test neg, what is the prob that they do not have the condition

ID those who do not have the disease among those who have a neg test result

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

positive LR addresses

A

how much more likely is a positive test found in someone with the disease than in someone without it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

negative LR addresses

A

how much more likely is a neg found in someone without the disease compare to someone who has it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

is sensitivity a true positive or true negative rate

A

true positive

test with high sensitivity have few false negatives

therefore neg result rule out the condition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

is specificity a true positive or true negative rate

A

true negative

have few false positives so if you have a positive it rules in the conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

false positives impact spin or snout

A

spin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

false negative impact spin or snout

A

snout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the difference between sn/sp and PPV/NPV - sn/sp

A

calculated from those who have the disease and those who do not

stable regardless of the disease prevelence in different populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the difference between sn/sp and PPV/NPV - PPV/NPV

A

calculated from those who are positive and those who are negative

influence by disease prevelance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

pre test and post test sn/sp

A

sn/sp do not provide us information on shift from pre and post test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

LR and pre and post test

A

these can tell about the shift pre and post test

qualifies the shift from pre and post test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does LR examine

A

how likely the disease is given a positive or negative test result

18
Q

postive LR - what does it tell us

A

given a positive test, are the odds the odds of having the condition larger

expresses the change in odds favoring the condition during a positive test

19
Q

negative LR - what does it tell us

A

express the changes in odds favoring the codition given a neg result

given a neg result, are the odds of the condition smaller

20
Q

what is pre test probality

A

what we know before applying the diagnostic test

clinician best guess

21
Q

post test probability

A

what we know after applying the DTI

can be quatified by using LR

22
Q

large positive LR indicates what

A

the condition is more likely

23
Q

small negative LR indicates what

A

the condition is less likely

24
Q

high specificity and +LR

A

larger + LR

due to the low false positive rate

25
high sensitivity and -LR
small -LR rate due to low false negative
26
how can we tell the precision of the diagnostic accuracy esitmates
CI - do not want to cross 0
27
if you have a larger CI is your information precise
no
28
over all what is the reason why we use LR
show the change in probability pre and post test
29
how do you know if a diagnostic test is reliable, accurate, and precise
is the test reproducible - good intra and inter rater reliablity how accurate is the test (sn, sp, LR)
30
Intrarater reliability
how consistent an individual is at measuring a constant phenomenon
31
interrater reliability
how consistent different individuals are at measuring the same phenomenon
32
what % of sp or sn is good
80
33
sp + sn test to avoid
do not equal at least 100
34
what is youdans index
showing the diagnostic perfromance of a test sn + sp - 1 >.5 (ideally 1)
35
what is a reciever operant curve
used when there is an overlap between those with or without a presentation graphic method to calculate sn and sp when a range of test scores are bing considered
36
what is an ROC used for
determine the optimal cut value between healthy and disease states determine the MCID
37
what is plotted on ROC's
true positive rate vs false positive rate
38
where is the optimal threshold value found in ROC
in the point closest to the upper left corner
39
what does the area under thee curve depend on
the true positive rate
40
a large area under the curve tells us what
better diagnostic accuracy
41
what happens if the AUC is a flat line
this is a worthless test AUC = .5