Determining common knowledge in an unfamiliar field What is the best strategy to determine common knowledge in an unfamiliar field? I have provided an example below, but I am not looking for an answer specific to that example.

We have an answered question that addresses whether and how common knowledge should be cited. A more difficult problem is determining what is common knowledge in an unfamiliar field. In my answer to the question linked, I provide one strategy, examining introductory textbooks in that field. However, as was mentioned in the comments, not all fields have introductory texts.

As an example, I am working on an institutional grant proposal. The proposed activities have to do with increasing retention rates of freshmen students, particularly in the sciences. We are looking at targeting pedagogical reform in introductory classes and increasing engagement through more and better co-curricular experiences. 

My background is in chemistry. I do not know what is common knowledge in the worlds of pedagogy and student engagement/retention. I have been reading books and articles on the subjects, and citation practices have been inconsistent. Some authors provide citations for everything, including broad generalizations and common sense, like:


  
  There are many reasons why an undergraduate student may choose to leave college.
  


And then others provide very few citations, including for statements that seem like they should have been based on a study:


  
  More than half of all students who withdraw from college are freshmen.
  Less than half of the students who declare science majors will graduate with a degree in a science field.
  


I realize that the former case may be from overzealous paranoia about plagiarism, and the latter case may be an example of poor scholarship, but this is difficult to assess as an outsider.

EDIT: For clarification, I am asking about determining when something requires a citation if I am writing in a field that I do not normally participate in. I know that I should always cite things that are new, obscure, or counter to prevailing thought. I wouldn't necessarily need to cite things that are "well-established" or "agreed-upon". After a certain point, if enough studies have reaffirmed the same result, or if the result has been so widely cited that it becomes well-known, it is pointless to cite it. It is currently silly to provide a citation for "The structure of DNA is a double helix formed by two complimentary strands held together by hydrogen-bonding between the base pairs." At one point, however, it was not silly, because this idea was new. 

How can I quickly determine where a finding is on the continuum between new/obscure and well established?
By far the simplest way to get around this problem is to simply give it to a colleague who is more well-versed in the field and have them judge which statements need to be backed up by citations and which don't.

The next simplest way is to read papers on a very similar topic to yours (which, no doubt, do exist) and see what they cite.

On a related note, my advisor gave me the advice of "when in doubt, cite." His point was that the only real downside of an unnecessary reference is added length to the paper. If you get to that point, and the only thing left to cut is citations, then you can start to worry.