Sensitivity and Specificity

Ensures the accuracy of your calculation of sensitivity, specificity, and predictive value

2x2 tables

Preferred percentage for sensitivity and specificity

90%

Sensitivity formula

A / A + C

Specificity formula

D / B + D

C

False Negative

Type II error

False Negative (C)

B

False Positive

Type I error

False Positive (B)

Likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that that same result would be expected in a patient without the target disorder

Likelihood ratio

pretest probability likelihood ratio

Measurement of disease probabiltiy

sensitivity specificity

Measurement of test accuracy

percentage chance that a positive test result is a true positive (actually have the disease)

PV+ or PPV

NPV formula

TN / all that tested negative ----> D / C + D

PPV formula

TP / all that tested positive ----> A / A + B

D

True Negative

A

True Positive

Used to determine the presence or absence of disease when a subject shows signs or symptoms of the disease

diagnostic tests

The higher the sensitivity and specificity are, the less chance of _________ results and improvement of PPV

false

Prevalence ratio formula

number of people with disease/ number of people tested x100

PV- or NPV

percentage chance that a negative test result is a true negative (are actually disease free)

Likelihood ration formula

positive test with disease / positive test without disease or sensitivity / 1 - specificity

Sensitivity

proportion of patients with a disease who test positive

Specificity

proportion of patients without a disease who test negative

Identifies asymptomatic individuals who may have the disease

screening

Gold Standard

the best test available to test for that disease

Ability of a test to indicate which individuals have the disease and which do not

validity