1B Stats

Question 1

Gold standard is

Answer 1

most reliable and accurate test (compare other tests to this test)

Question 2

degree to which instrument measures what it says it does

Answer 2

validity

Question 3

degree to which measurement is free from error

Answer 3

reliability

Question 4

ability to detect change over time in measured construct

Answer 4

responsiveness

Question 5

contingency table for diagnostic test: a

Answer 5

a =true positive

Question 6

b =

Answer 6

false positive

Question 7

c =

Answer 7

false negative

Question 8

d =

Answer 8

true negative

Question 9

given that individual has condition, probability that test is +

Answer 9

sensitivity

Question 10

given that individual does not have condition, probability that test will be negative

Answer 10

specificity

Question 11

true + rate

Answer 11

sensitivity

Question 12

true - rate

Answer 12

specificity

Question 13

sensitivity equation

Answer 13

a/a+c

true positives/true pos + false neg (ALL COND POS)

Question 14

specificity equation

Answer 14

d/(b+d)
true neg/ false pos+true neg (ALL COND NEG)

Question 15

given that test result is positive, probability that individual has condition

Answer 15

+ predictive value

Question 16

given that test result is negative, probability that individual DOES NOT have condition

Answer 16

• predictive value

Question 17

+ predictive value equation

Answer 17

a/a+b
true positive/ALL TEST POS

Question 18

-pred value equation

Answer 18

d/c+d

true neg/false neg+true neg (ALL TEST NEG)

Question 19

condition with low prevalence will have

Answer 19

lower +PV
higher -PV

Question 20

likelihood ratios combine

Answer 20

sensitivity and specificity values

Question 21

positive LR

Answer 21

sensitivity/(1-specificity)

Question 22

negative LR

Answer 22

1-sensitivity/specificity

Question 23

higher positive LR

Answer 23

more certain that patient HAS condition if test is positive!

ratio of true + to false +

Question 24

lower negative LR

Answer 24

odds that individual has condition is SMALLER
ratio of false neg to true neg

Question 25

If LR is over 10
If -LR is smaller than 0.1

Answer 25

large, conclusive shifts in probability!

Question 26

moderate shifts in probability

Answer 26

LR: 5-10
-LR: 0.1-0.2

Question 27

small likelihood ratio

Answer 27

+LR: 1-2 (close to 1)
-LR: 0.5-1 (close to 1)

Question 28

increased ______(reliability/validity) of a test decreases the ____value in that pop

Answer 28

RELIABILITY
MDC

Question 29

What is the most powerful tool for quantifying importance of a test?

Answer 29

Likelihood ratio!

importance of positive and negative test results can be examined indiependently!

Question 30

Reliability measures of change

Answer 30

MDC and MCID
MDC: amount of change needed to exceed measurement error of test
MCID: amount of change that is significant to patient’s improvement