( ( ( ( ( ( Identify and ) select ) ( ( experimental variables ) ( -LRB- ( ( ( independent and ) dependent ) -RRB- ) ) ) ) and ) ( controlled conditions ) ) . )
(ROOT (S (VP (VP (VB Identify) (CC and) (VB select) (NP (NP (JJ experimental) (NNS variables)) (PRN (-LRB- -LRB-) (ADJP (JJ independent) (CC and) (JJ dependent)) (-RRB- -RRB-)))) (CC and) (VP (VBN controlled) (NP (NNS conditions)))) (. .)))
Identify and select experimental variables (independent and dependent) and controlled conditions.
(ROOT (S (NP (NP (DT The) (NNS values)) (PP (IN of) (NP (JJ independent) (NNS variables)))) (VP (VBP are) (VP (VBN controlled) (PP (IN by) (NP (NP (DT the) (NN experimenter)) (PP (IN over) (NP (NP (DT the) (NN course)) (PP (IN of) (NP (DT an) (NN experiment))))))))) (. .)))