A reporter included some statistics in a story about school bus delays:
While almost 65 percent of these delays were caused by heavy traffic, mechanical problems and buses not starting accounted for nearly 14 percent of the total.
After editing, the sentence appeared this way:
While almost 65 percent of these delays were caused by either heavy traffic or mechanical problems, buses not even starting accounted for nearly 14 percent of the total.
Neither version is healthy. The role of “mechanical problems” was supposed to be associated with 14 percent of the delays, not 65 percent. The sentence had fallen victim to “prepositional phrase without end,” or “PPWE” (pronounced “pee-pee-WEE”).
This affliction can occur without warning, in any kind of writing. It has many causes, among them a hurried writer, an editor who makes change without questioning what was intended, and a failure to understand how readers digest sentences. Its symptoms include confused readers and unclear comprehension.
PPWE is treatable, curable, and even avoidable with proper exercise of care. Treatment and cure can include moving the prepositional phrase to the end of the sentence to see if the sentence survives without multiple side effects, or performing a total resection of the sentence (aka rewriting it).
These statements have not been evaluated by the Food and Drug Administration. This column is not intended to diagnose, treat, cure, or prevent any disease. So let’s switch to layman’s terms.
The original sentence opened with a prepositional phrase, “While almost 65 percent of these delays were caused by….” Nothing wrong there: The “while” signals to a reader that there is more to this than the opening phrase may indicate. But then comes a grouping of nouns: “traffic, mechanical problems and buses not starting.” That reads at first like a series of three things that make up 65 percent of the delays. (A serial comma might have helped, or not.) A reader can then easily stumble when encountering another verb, “accounted.” That means the reader must back up and reprocess what part(s) of “traffic, mechanical problems and buses not starting” go(es) with “accounted,” and what part(s) belong(s) in the prepositional phrase, with the verb “were caused.”
For want of a clear end to the prepositional phrase, clarity was lost.
While nothing is wrong with starting a sentence with a prepositional phrase, it’s important to pay attention to where it ends. To begin with, you often want to end it with a comma. The Purdue Online Writing Lab recommends adding a comma when the prepositional phrase at the beginning of a sentence is more than four words, but the more important measurement is how a reader will experience it. The previous sentence, for example, began with the prepositional phrase “To begin with,” which under OWL guidelines would not call for a comma. Without it, though, the reader can momentarily stumble reading the phrase “To begin with you….” The comma signals the end of the prepositional phrase and the beginning of the heart of the sentence. (Remember that a prepositional phrase is not the main clause of the sentence, and so should not contain the main point the sentence is trying to make.)
Earlier, we mentioned two treatments or cures for PPWE. One is to move the prepositional phrase to the end of the sentence to see if the sentence survives. In our troubled patient, had the writer tried it, the problem might not have been obvious, because the writer knew what was meant:
Mechanical problems and buses not starting accounted for nearly 14 percent of the total, while almost 65 percent of these delays were caused by heavy traffic.
The editor, though, would have had to experiment to see where the phrase ended, and might have thought this worked, with a slight change:
Buses not starting accounted for nearly 14 percent of the total, while almost 65 percent of these delays were caused by heavy traffic [or] mechanical problems.
Arthroscopic surgery (or a semicolonoscopy) on the original would have helped immensely:
Almost 65 percent of these delays were caused by heavy traffic; mechanical problems and buses not starting accounted for nearly 14 percent of the total.
But to keep that “contrast” of the larger share of problems to the smaller, the writer had only to keep the sentence structure parallel:
While almost 65 percent of these delays were caused by heavy traffic, nearly 14 percent of the delays were caused by mechanical problems and buses not starting.
That’s another “cure” for long prepositional phrases with verbs of their own: Make sure what follows the phrase is structured similarly. If the prepositional phrase is setting up a contrast or similarity, having a parallel structure better allows the reader to make the comparison without having to adjust to a new structure.
We can eliminate the scourge of PPWE in our lifetime, if we all do our part.