Psychometric Properties

Question 1

Validity

Answer 1

-how correct it is
-measures what it should
-cannot exit without reliability

Question 2

Reliabiliy

Answer 2

-how consistent it is
-degree of association
-can exist without validity

Question 3

Contingency Table

Answer 3

True Positive: a; tested positive with test; have the condition

False Positive: b; tested positive; don’t have the condition

False Negative: c; tested negative; have the condition

True Negative: d; tested negative; don’t have condition

Question 4

Sensitivity

Answer 4

-snout: rule out
-true positive test
-shows all the positive so it rules out the negatives
-a/(a+c)

Question 5

Specificity

Answer 5

-spin: rule in
-true negative
-shows all the negative so it rules in the positives
-d/(b+d)

Question 6

Predictive Value (+)

Answer 6

-likelyhood that the positive test = having condition
-a/(a+b)

Question 7

Predictive Value (-)

Answer 7

-likelyhood that the negative test= not having condition
-d/(c+d)

Question 8

Positive Likelihood Ratio

Answer 8

-increased odds of having condition if testing positive
-ratio of true to false
-Sensitivity/ (1- Specificity)
-higher= more likely

Question 9

Negative Likelihood Ratio

Answer 9

-decreased odds of having condition if testing negative
-ratio of false to true
-(1- Sensitivity)/ Specificity
-lower= less likely

Question 10

Guide to Interpreting LR

Answer 10

-most powerful tool for quantifying importance of a particular test

> 10/<0.10: large probability
5-10/0.5-1: moderate
2-5/0.2-0.5: small
1-2/0.5-1: rare

Question 11

Minimal Detectable Change

Answer 11

-MDC
-amount of change needed to overcome measurement error
-increase reliability of test decreases MDC

Question 12

Minimal Clinical Important Difference

Answer 12

-MCID
-amount of important change from the perspective of individual
-should be bigger than MDC