MLU v.s. MLR...what do you think?

[Corinna Butt]

Does anyone know of studies or literature which compare mean length
utterance (in morphemes) to mean length of response (the average number
of WORDS per utterance)?  I am wondering how much of a difference there
is between scores derived from each measure for a whole langauge sample
(specifically, the langauge of a normal preschool age child with an MLU
of 1.00 to 4.5 or so). If anyone can provide some references which
address this topic, or if anyone has any thoughts on the matter, your
input would be very much appreciated! Thank you .
Corinna