There are many students who struggle with their writing. They are not able to put their thoughts, their ideas and their research cogently and clearly down on paper. This is especially true in the case of students for whom English is not their native language.
There are many students in countries like Singapore who take their courses in English. But their native language is not English. It might be Mandarin or Malay or Tamil. However, since the quality of academic research in English is very high, they prefer to take their courses in English. However, when the time comes for them to do their projects they struggle with the language. Their professors insist that the quality of the language used in their writing has to be very high. The students know that when they write there will be plenty of grammatical and linguistic mistakes. That is when the skills of a substantive editor help them.
This is the type of editor who makes sure that the language employed by the students correctly conveys the message that they intend to convey and their material employs a very high standard of language. The editor looks through the sequence of the material that has been written and makes sure that one point logically follows the next. Then he makes sure that all the data and all the statistics have been presented properly and the words that have been used describe the information in the right way.
Then there is the question of the grammatical construction of the sentences and this is where the students tend to make many mistakes. The grammar is looked over thoroughly and only when all the mistakes have been completely rectified will the editor feel as though his job has been done and the students can confidently present their material to the review board.