Sensitivity and Specificity in Imaging Flashcards
what is in the usefulness/accuracy of a diagnostic test
the ability of of the test to detect a person with the disease and to exclude the a person without the disease
what is sensitivity
the ability to detect disease in someone with the disease
what does sensitivity tell us
how well a positive test result detects disease
what is sensitivity equal to
= proportion of people with the disease who have a positive test result
sensitivity %
sensitivity % = no. of people with disease who tested positive / total number of people with disease
what is specificty
how likely the test is to rule out disease in someone without the disease
what does specificity tell us
how well a negative test result detects no disease
what is specificity equal to
= the proportion of people without the disease who will have a negative result
specificity %
specificity % = number of people without disease that tested negative / total number of people without disease
what does a true positive result mean
sick person correctly identified as sick
what does a false positive result mean
healthy person is incorrectly identified as sick
what does a false negative result mean
a sick person is incorrectly identified as healthy
what does a true negative result mean
a healthy person is correctly identified as healthy
what is positive predictive value (PPV)?
how likely is someone with a positive test result to actually have the disease
what is positive predictive value equal to
= the proportion of people with a positive test result to actually have the disease
