It is important to note also that this product was not promoted at retail with discounted prices at any time during this period, so the variation is not due to consumers preferring to purchase a product when it was  on sale. 
( ( ( ( ( It ( is ( important ( to ( ( note also ) ( that ( ( this product ) ( ( was not ) ( ( ( promoted ( at ( retail ( with ( discounted prices ) ) ) ) ) ( at ( any time ) ) ) ( during ( this period ) ) ) ) ) ) ) ) ) ) ) , ) so ) ( ( the variation ) ( ( is not ) ( due ( to ( consumers ( preferring ( to ( ( purchase ( a product ) ) ( when ( it ( was ( on sale ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (PRP It)) (VP (VBZ is) (ADJP (JJ important) (S (VP (TO to) (VP (VB note) (ADVP (RB also)) (SBAR (IN that) (S (NP (DT this) (NN product)) (VP (VBD was) (RB not) (VP (VBN promoted) (PP (IN at) (NP (NP (JJ retail)) (PP (IN with) (NP (JJ discounted) (NNS prices))))) (PP (IN at) (NP (DT any) (NN time))) (PP (IN during) (NP (DT this) (NN period))))))))))))) (, ,) (IN so) (S (NP (DT the) (NN variation)) (VP (VBZ is) (RB not) (ADJP (JJ due) (PP (TO to) (NP (NP (NNS consumers)) (VP (VBG preferring) (S (VP (TO to) (VP (VB purchase) (NP (DT a) (NN product)) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBD was) (PP (IN on) (NP (NN sale))))))))))))))) (. .)))
The product was offered on sale for the majority of this time period.
( ( The product ) ( ( was ( offered ( on ( sale ( for ( ( the majority ) ( of ( this ( time period ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN product)) (VP (VBD was) (VP (VBN offered) (PP (IN on) (NP (NP (NN sale)) (PP (IN for) (NP (NP (DT the) (NN majority)) (PP (IN of) (NP (DT this) (NN time) (NN period))))))))) (. .)))