Some grammar experts claim that the fewer prepositions the better, and this check warns you if the ratio of prepositions is more than 1 preposition per 5 words.
Abundant prepositions: The data from the participants of younger age in this study were compared with those of subjects of older age by an analysis of variance.
“Healthy” ratio of prepositions: The data from the younger and older study participants were compared by an analysis of variance