( ( ( The factor ) ( that ( is ( manipulated ( in ( an experiment ) ) ) ) ) ) ( ( is ( the ( independent variable ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN factor)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN manipulated) (PP (IN in) (NP (DT an) (NN experiment)))))))) (VP (VBZ is) (NP (DT the) (JJ independent) (NN variable))) (. .)))
The factor that is manipulated in an experiment is the independent variable .
(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))))))) (. .)))