A participial phrase at the beginning of a sentence must refer to the grammatical subject. Strunk & White, p. 13.But many people seem to have trouble following this rule. The rule actually applies more broadly, goes beyond a participial phrase, and applies to any introductory adjectival phrase. Whenever you introduce a sentence with any adjectival phrase, that phrase must modify the grammatical subject of the sentence.
When arguing for this approach, statistical research must be cited.Note that the grammatical subject, statistical research, is not the agent (the do-or) of arguing. A person or organization capable of human thought must do the arguing. Here’s the revision:
When arguing for this approach, the committee must cite statistical research.Watch Out for the Passive Voice
When arguing . . . research must be cited . . . .I see these structures pop up all the time. They are at war with each other. First, the passive-voice verb boots the actor or agent out of the sentence. Then the present-participial phrase pleads for the opposite.
Catching a pass, the winning touchdown was made.So when you’re tempted to say, when arguing . . . research must be cited, remember the superiority of the active voice and the strong desire the present participle has for its actor, bring the actor back into your writing, and say:
When arguing for this approach, the committee must cite statistical research.After all:
Catching the pass, Santana Moss scored the winning touchdown.Click page 2 below. Introductory -ed Phrase
Shown at the mall, many people saw Titanic.Notice that the introductory past participle, shown, does not modify the grammatical subject of the sentence, many people. Instead, it modifies the direct object, Titanic. The participle must modify the grammatical subject. Otherwise, it dangles. Here’s the revision:
Shown at the mall, Titanic attracted many people.A Problem with Based on
Based on our research, we decided to adopt this policy.As you can see, we are not based on our research. The writer is trying to modify the verb decided to adopt. But the introductory past participle must act as an adjective and must modify the grammatical subject. It cannot act as an adverb and modify the verb decided to adopt.
As a result of our research, we decided to adopt this policy.Henry Fowler urges:
[Writers should] avoid using Based on as a kind of sentence-leading preposition: Based on this assumption, the economy is not expected to improve before the autumn. The relationship between Based on and the economy is not a direct one. New Fowler, p. 94.I think New Fowler could have gone further and pointed out that based is a past participle, which requires the recipient of the "basing" to serve as the grammatical subject of the sentence.