( ( ( Independent variables ) ( Those variables ) ) ( ( controlled ( by ( the experimenter ) ) ) . ) )
(ROOT (S (NP (NP (JJ Independent) (NNS variables)) (NP (DT Those) (NNS variables))) (VP (VBN controlled) (PP (IN by) (NP (DT the) (NN experimenter)))) (. .)))
Independent variables Those variables controlled 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))))))))) (. .)))