Changes

==Interpretation of diagnostic tests==

==Interpretation of diagnostic tests==

Several statistics can aid clincians in the interpretation of diagnostic tests these include '''sensitivity''' and '''specificity''', '''predictive values''', '''likelihood ratios''' and '''pre-''' and '''post-test probabilities'''. The following 2 x 2 table is often used by epidemiologists to calculate these statistics:

Several statistics can aid clinicians in the interpretation of diagnostic tests these include '''sensitivity''' and '''specificity''', '''predictive values''', '''likelihood ratios''' and '''pre-''' and '''post-test probabilities'''. The following 2 x 2 table is often used by epidemiologists to calculate these statistics:

[[File:table.jpg]]

[[File:table.jpg]]

'''Sensitivity (''Se'')''' is the probability that a positive animal is correctly identified as positive and '''specificity (''Sp'')''' is the probability a negative animal is correctly identified as negative.

'''Sensitivity (''Se'')''' is the probability that a positive animal is correctly identified as positive and '''specificity (''Sp'')''' is the probability a negative animal is correctly identified as negative.

===Predictive values===

===Predictive values===

There are two types of predictive value; '''positive predictive value (PV+)''' is defined as the probability that an animal which tests positive actually has the disease and '''negative predictive value (PV-)''' is the probability and animal that tests negative does not have the disease. PV+ and PV- are calculated as follows:

There are two types of predictive value; '''positive predictive value (PV+)''' is defined as the probability that an animal which tests positive actually has the disease and '''negative predictive value (PV-)''' is the probability and animal that tests negative does not have the disease. PV+ and PV- are calculated as follows:

===Likelihood ratio===

===Likelihood ratio===