4) Not enough is known about how nontransportation costs vary with distance.
( ( 4 -RRB- ) ( ( Not enough ) ( ( is ( known ( about ( how ( ( nontransportation costs ) ( vary ( with distance ) ) ) ) ) ) ) . ) ) )
(ROOT (S (LST (LS 4) (-RRB- -RRB-)) (NP (RB Not) (JJ enough)) (VP (VBZ is) (VP (VBN known) (PP (IN about) (SBAR (WHADVP (WRB how)) (S (NP (NN nontransportation) (NNS costs)) (VP (VBP vary) (PP (IN with) (NP (NN distance))))))))) (. .)))
The reason for the lack of information is the fact that what goes into nontransportation costs can differ dramatically by individual.
( ( ( The reason ) ( for ( ( the lack ) ( of information ) ) ) ) ( ( ( is ( the fact ) ) ( that ( ( what ( goes ( into ( nontransportation costs ) ) ) ) ( can ( ( differ dramatically ) ( by individual ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN reason)) (PP (IN for) (NP (NP (DT the) (NN lack)) (PP (IN of) (NP (NN information)))))) (VP (VBZ is) (NP (DT the) (NN fact)) (SBAR (IN that) (S (SBAR (WHNP (WP what)) (S (VP (VBZ goes) (PP (IN into) (NP (NN nontransportation) (NNS costs)))))) (VP (MD can) (VP (VB differ) (ADVP (RB dramatically)) (PP (IN by) (NP (NN individual)))))))) (. .)))