Can 'using' correctly be used as a preposition in the beginning of the sentence and if so, is this structure natural, formal ? What are other alternatives. Here's the example:
Using ..., somebody did something
Using the results of the analysis, we assigned ambiguous items to specific factors and removed unstable items.
Sure. It is fairly common to put a prepositional phrase like that at the beginning of a sentence.
Putting words at the beginning of a sentence tends to give them more emphasis. We sometimes also want to put words at the end to create some surprise or tension -- sometimes quite literally add some surprise, like if we are revealing some previously unknown fact or telling a joke.
"I ate my breakfast using a fork." "Using a fork, I ate my breakfast." Both mean essentially the same thing. The second puts some emphasis on the fact that I used a fork. As opposed, I suppose, to using a spoon or my fingers or whatever.
"Last Thursday, in my best friend's bedroom, I saw my wife." Arranging the sentence to put the word "wife" last helps to build some tension as to just who I saw in the room. (It would be more effective if the sentence was longer to draw it out further.) "I saw my wife in my best friend's bedroom last Thursday." This is less effective. The fact that it was last Thursday is probably the least interesting thing in the sentence, so putting that last does not build any tension.
"Using the results of the analysis, we assigned ambiguous items to specific factors and removed unstable items."
"Using" there is a verb, in present participle form, used adverbially, i.e. in an adverbial phrase, where normally you would expect an adverb (hence your confusion). In these cases the subject of the adverbial clause is understood to be the same as the subject in the main clause.
