Final: Lecture 20 Flashcards
What is a true positive?
Test reports a positive result in a patient that DOES have the disease
what is a true negative?
Test reports a negative result in a patient that DOES NOT have the disease
What is a false positive?
Test reports a positive result in a patient that DOES NOT have the disease
What is a false negative?
Test reports a negative result in a patient that DOES have the disease
What is sensitivity?
How well a test can detect disease, if disease is present
What is specificity?
How well a test can detect absence of disease, if disease is absent
What is the positive predictive value?
How accurately a positive test predicts the presence of disease
What box in the 2x2 table represents the TP, FP, TN, FN
TP- A
FP- B
TN- D
FN- C
How do you calculate specificity?
TP/All diseased
A/A+C
How do you calculate sensitivity?
TN/All not diseased
D/B+D
How do you calculate positive predictive value?
TP/All positive tests
A/A+B
What is the negative predictive value?
How accurately a negative test predicts the absence of disease
How do you calculate negative predictive value?
TN/All negative tests
D/C+D
What is diagnostic accuracy/precision?
Proportion of time a patient is correctly identified as either having disease or not having disease
How do you calculate diagnostic accuracy/precision?
(TP+TN)/All patients
(A+D)/A+B+C+D
What is the likelihood ratio positive?
Probability of positive test in presence of disease/Probability of positive test in absence of disease
What is the likelihood ratio negative?
Probability of negative test in presence of disease/Probability of negative test in absence of disease
How do you calculate likelihood ratio positive?
Sensitivity/(1-specificity)
How do you calculate likelihood ratio negative?
(1-sensitivity)/Specificity
What is the bottom line value for data to be called either LR+ or LR-?
LR+ should be >10
LR- should be <0.1
What is validity?
Ability to accurately tell between those who DO have disease and those who DO NOT have disease
What is internal validity?
Extent the results accurately reflect the true situation of the study population
What is external validity?
Extent the results are applicable to other populations not included in the study
What is reliability?
Ability of a test to give the same result on repeated uses
