( Second ( , ( one ( ( must ( calculate ( ( how often ) ( ( ( a test ) ( that ( should ( be negative ) ) ) ) ( will ( produce ( a ( ( falsely positive ) ( test result ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (LS Second)) (, ,) (NP (PRP one)) (VP (MD must) (VP (VB calculate) (SBAR (WHADVP (WRB how) (RB often)) (S (NP (NP (DT a) (NN test)) (SBAR (WHNP (WDT that)) (S (VP (MD should) (VP (VB be) (ADJP (JJ negative))))))) (VP (MD will) (VP (VB produce) (NP (DT a) (ADJP (ADVP (RB falsely)) (JJ positive)) (NN test) (NN result)))))))) (. .)))
Second, one must calculate how often a test that should be negative will produce a falsely positive test result.
(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))))))))))) (. .)))