Ultrasound Physics: Statistics Flashcards
Gold standard
An exam upon which other exams are compared to
Comparison exam
Any exam that’s compared to the gold standard
Test validation
Set of statistics used to compare ultrasound against the gold standard
Reliability
Getting consistent results under the same circumstances
What is considered a reliable comparison exam?
When it’s an 80-90% match to the gold standard
What are the types of test validations? (6)
- sensitivity
- specificity
- accuracy
- positive predictive value
- negative predictive value
- prevalence
Chi square
Statistical test that compares the differences between what you find on the gold standard exam & what was found on the ultrasound scan
True positive (TP)
Comparison exam correctly predicts there’s disease when gold standard predicts disease
False positive (FP)
Comparison test predicts there’s disease but gold standard doesn’t
True negative (TN)
Comparison test correctly predicts there isn’t disease when gold standard also predicts there is no disease
False negative (FN)
Comparison test predicts there’s no disease but there actually is
Accuracy & equation
Overall percentage of times a comparison test is right
TP + TN / total exams
Positive predictive value & equation
Percentage of times a test is correct when positive for disease
TP / TP + FP
Negative predictive value & equation
Percentage of times a test is correct when negative for disease
TN / TN + FN
Prevalence & equation
Percentage of population that has disease
TP + FN / total exams
