Assessment of Diagnostic Techniques

Question 1

What is the equation for diagnostic sensitivity?

Answer 1

true positives / #true positives + #false negatives

i.e. how many animals with disease does the test pick up on

Question 2

What is the equation for diagnostic accuracy?

Answer 2

true positives + #true negatives / total # of animals

i.e. how many animals does the test correctly categorise as having/not having disease

Question 3

What is the equation for diagnostic specificity?

Answer 3

true negatives / #true negatives + #false positives

i.e. how many animals without disease does the test correctly identify.

Question 4

What do predictive values of positive/negative results indicate?

Answer 4

These predict how likely a positive/negative result of a test is to be truly positive/negative.

Question 5

What is the equation for the predictive value of a positive result?

Answer 5

TP / #TP + #FP