Contents of this section: Statistical Terms used in Medical Studies





 

Gold standard Positive (condition present)

Gold standard Negative (condition not present)

Test result Positive

True Positive

False Positive

Test result Negative

False Negative

True Negative




Stable Properties:



Sensitivity = True Positives/(True Positives + False Negatives)


Specificity = True Negatives/(False Positive + True Negative)



Frequency Dependent Properties:



Positive Predictive Value = True Positive/(True Positive + False Positive)


Negative Predictive Value = True Negative/(True Negative + False Negative)



Likelihood Ratios



The likelihood ratio for a test result compares the likelihood of that result in patients with disease to the likelihood of that result in patients without disease:



 

Condition Present

Condition Absent

Test Positive

a

b

Test Negative

c

d



Positive LR = (a/a+c)/(b/b+d)
Negative LR = (c/a+c)/(d/b+d)


How much do Likelihood Ratios change disease likelihood?


LRs >10 or <0.1 cause large changes in likelihood.
LRs 5-10 or 0.1-0.2 cause moderate changes.
LRs 2-5 or 0.2-0.5 cause small changes.
LRs between <2 and 0.5 cause little or no change.



•  Basics of OAES  •  Biophysics and OAEs  •    Neonatal Screening  •    Clinical Applications of OAEs  •    New methods for OAE signal analysis  •    Statistical terms in medical studies  •  Main