By the late 1980s, a growing number of retailers had started changing the way they did business.
( ( By ( the ( late 1980s ) ) ) ( , ( ( ( a ( growing number ) ) ( of retailers ) ) ( ( had ( started ( changing ( ( the way ) ( they ( did business ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN By) (NP (DT the) (JJ late) (NNS 1980s))) (, ,) (NP (NP (DT a) (VBG growing) (NN number)) (PP (IN of) (NP (NNS retailers)))) (VP (VBD had) (VP (VBN started) (S (VP (VBG changing) (NP (NP (DT the) (NN way)) (SBAR (S (NP (PRP they)) (VP (VBD did) (NP (NN business)))))))))) (. .)))
Retailers began to change their business tactics in the late 1980s.
( Retailers ( ( began ( to ( ( change ( their ( business tactics ) ) ) ( in ( the ( late 1980s ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Retailers)) (VP (VBD began) (S (VP (TO to) (VP (VB change) (NP (PRP$ their) (NN business) (NNS tactics)) (PP (IN in) (NP (DT the) (JJ late) (NNS 1980s))))))) (. .)))