( ( A ( dependent variable ) ) ( ( is ( ( ( what ( you ( measure ( in ( the experiment ) ) ) ) ) and ) ( what ( is ( affected ( during ( the experiment ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (JJ dependent) (NN variable)) (VP (VBZ is) (SBAR (SBAR (WHNP (WP what)) (S (NP (PRP you)) (VP (VB measure) (PP (IN in) (NP (DT the) (NN experiment)))))) (CC and) (SBAR (WHNP (WP what)) (S (VP (VBZ is) (VP (VBN affected) (PP (IN during) (NP (DT the) (NN experiment))))))))) (. .)))
A dependent variable is what you measure in the experiment and what is affected     during the experiment.
(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))))))) (. .)))