Diagnostic Accuracy Flashcards
What is reliability
Produces precise, accurate, and reproducible information
What is diagnostic accuracy
Ability to discriminate between patients with and without a specific disorder
What is pretest
The likelihood that a patient exhibits a specific disorder before the physical exam commences
What is the posttest
Likelihood that a patient has a specific disorder after the clinical exam test has been performed
What are the 4 types of data
- Nominal
- Ordinal
- Interval
- Ratio
What is nominal data
Groupings/place holder
What is ordinal data
Quantities that have a natural order, but cannot state with any certainty whether intervals between values are equal
What does the Kappa coefficient do
Removes random selection or guessing that occurred
What Kappa coefficient is good reliabilitity
Greater than 0.75
What Kappa coefficient is moderate reliabilitiy
0.50-0.75
What Kappa coefficient is poor reliability
Less than 0.50
What is interrater reliability
Reliability between raters
What is intrarater reliability
Reliability within a single rater
What is interval data
Order with equal intervals but without an absolute zero point
What is ratio data
Order with equal intervals and an absolute zero
What does Pearson (r) do
Analyzes association between 2 measurements
What is a true positive
Positive and present
What is a true negative
Negative and not present
What is a false positive
Positive and not present
What is a false negative
Negative and present
What is influenced by prevalence or total instances of a diagnosis in the population at a given time, sex ratios, or severity of disease
Spectrum Bias
What does a positive predictive value do
Estimates the likelihood that a pt with a positive test actually has the disease
What does a negative predictive value do
Estimates the likelihood that a pt with a negative test actually does not have the disease
What is sensitivity
A measure of true positive rate
What is specificity
A measure of true negative rate
What does SnNOUT stand for
Sensitive test when negative rules out pt
What does SpPIN stand for
Specific test when positive rules in
What happens if the test is made less stringent
Increase of false positives will certainly increase and fewer cases will be missed
What happens to sensitivity and specificity if you make the test less stringent
Increase sensitivity
Decrease specificity
What happens if the test is made more stringent
A greater portion of those who are normal will test negative and a large number of true cases will be missed
What happens to sensitivity and specificity if you make the test more stringent
Decrease sensitivity
Increase specificity
What positive likelihood ratio is important
Greater than 10
What negative likelihood ratio is important
0-0.1
