( Independent ( ( variable ( ( The variable ) ( ( ( controlled or ) manipulated ) ( by ( the experimenter ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Independent)) (VP (VBZ variable) (NP (NP (DT The) (NN variable)) (VP (VBN controlled) (CC or) (VBN manipulated) (PP (IN by) (NP (DT the) (NN experimenter)))))) (. .)))
Independent variable The variable controlled or manipulated by the experimenter.
(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))))))))) (. .)))