( Experiment ( ( defines ( ( ( ( the ( interacting variables ) ) , ) or ) factors ) ) . ) )
(ROOT (S (NP (NNP Experiment)) (VP (VBZ defines) (NP (NP (DT the) (JJ interacting) (NNS variables)) (, ,) (CC or) (NP (NNS factors)))) (. .)))
Experiment defines the interacting variables, or  factors.
(ROOT (S (NP (JJ Dependent) (NN variable)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (DT the) (VBN affected) (NN factor)) (PP (IN in) (NP (DT an) (NN experiment))))))) (. .)))