Let's imagine we have an electronic dictionary - it doesn't matter if it's a webpage, a desktop application or a mobile app. The question might also apply to an encyclopaedia.
Every entry has the word (which was searched for) and the definition. An example entry could look something like this:
at home = chez soi, à la maison
Now we want the users who are searching the dictionary to contribute by suggesting better translations and marking wrong ones.
I could imagine several different ways to enable users to contribute. What would be the most efficient and valuable one?
On every entry page, let the user edit the current list of translations. = Highly valuable information as you can use the data exactly as they are entered by the user. BUT: A user who is searching for a word is probably not able to correct a this word on his own.
On every entry page, display a vote form so that the user can tell you which translation was the best or if all translations were inadequate.
Just offer a general form for users willing to contribute. In this form there is a random entry made editable.