( ( In ( most instances ) ) ( , ( ( a ( powerful ( diagnostic test ) ) ) ( ( should ( ( ( ( have ( a ( likelihood ( ratio close ) ) ) ) ( to ( ( ( 0 ( for ( a ( negative result ) ) ) ) and ) ( ( a ratio ) ( of ( ( at least ) 10 ) ) ) ) ) ) ( to 20 ) ) ( for ( ( a ( positive result ) ) ( -LRB- ( ( ( 27 , ) 31 ) -RRB- ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (JJS most) (NNS instances))) (, ,) (NP (DT a) (JJ powerful) (JJ diagnostic) (NN test)) (VP (MD should) (VP (VB have) (NP (DT a) (NN likelihood) (NN ratio) (NN close)) (PP (TO to) (NP (NP (NP (CD 0)) (PP (IN for) (NP (DT a) (JJ negative) (NN result)))) (CC and) (NP (NP (DT a) (NN ratio)) (PP (IN of) (NP (QP (IN at) (JJS least) (CD 10))))))) (PP (TO to) (NP (CD 20))) (PP (IN for) (NP (NP (DT a) (JJ positive) (NN result)) (PRN (-LRB- -LRB-) (NP (CD 27)) (, ,) (NP (CD 31)) (-RRB- -RRB-)))))) (. .)))
In most instances, a powerful diagnostic test should have a likelihood ratio close to 0 for a negative result and a ratio of at least 10 to 20 for a positive result (27, 31) .
(ROOT (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT an) (JJ incorrect) (NN test) (NN result)) (SBAR (WHNP (WDT that)) (S (VP (MD should) (VP (VB have) (VP (VBN been) (ADJP (JJ positive) (NP (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-)) (ADJP (JJ false) (JJ negative))))))))))) (. .)))