Let’s look closely at the sentence you presented:
“The percentage of people from couple-with-children family in poverty is 12%, slightly higher than the average, more 5 % than that of couple-without-children family, lower than the average.”
That sentence is actually the “reduced” form of the following complex sentence with a nonrestrictive or nonessential relative clause:
“The percentage of people from couple-with-children family in poverty is 12%,
which is slightly higher than the average, more 5 % than that of couple-without-children family,
and lower than the average.”
The main clause is, of course, ““The percentage of people from couple-with-children family in poverty is 12%”; and the nonrestrictive clause is “which is slightly higher than the average, more 5 % than that of couple-without-children family, and lower than the average.” This nonrestrictive clause functions as an adjective clause modifying its antecedent noun “12%” as its subject.
In the version you presented, however, the nonrestrictive clause has been reduced to a modifying phrase through the elimination of the relative pronoun “which” and the operative verb “is” in that clause. In English, adjective clauses that use the relative pronouns “who,” “which,” and “that” generally can be reduced by dropping the relative pronoun and the form of the verb “be” used in the adjective clause. The reduction, which is meant to make the sentence more concise, converts the adjective clause into an adjective phrase, which, of course, is a simpler construction than an adjective clause. The reduction, however, can be done only if it doesn’t alter or distort the intended meaning or sense of the sentence. (
Click this link to my previous posting in the Forum that discusses the reduction of adjective clauses to adjective phrases more extensively.)
In the “unreduced” version of the sentence you presented, there’s actually a series of three adjective clauses independently modifying “12%”, as follows:
1. “which is slightly higher than the average”
2. “which is more 5 % than that of couple-without-children family”; and
3. “which is lower than the average”
However, since they are constructed in serial enumerative form, only one “which is” is used for all of them. Of course, there should also be the conjunction “and” to indicate that the third item in the serial enumeration is the last, but this “and” was eliminated by the writer perhaps for stylistic purposes. This omission of “and” in such situations is called
asyndeton, which is sometimes resorted to by some writers for emphasis or dramatic effect.
I hope that this has adequately explained the structure of the sentence you presented.
