I am a 4th year Ph.D. Student. After submitting my first paper 6 months ago, I have been continuing that research. I have a lot of new methods and results, and I am almost ready to start writing again.
How do I know if I should split my research into two papers or write a single comprehensive paper? If I choose to split, how do I decide where best to split the two papers?
Without going into too much detail, I have a method that explains the causes of a fairly well studied phenomenon. I can show that there are four distinct causes of this phenomenon and explain the relative importance of each cause in different situations. If I split my research into papers 1 and 2, the conclusions of paper 1 may seem vague and inconclusive. If I combine my research into a single paper, it may be quite long and rambling. I want to choose a path that minimizes both of these problems.
My mental model for the situation is a tipi. Some of the concepts in that I need to write about have to lean on one another for support, like the tent poles of a tipi. If there are not enough concepts (or tent poles) the rest of the concepts fall short of a real conclusion; The tipi will fall over the first time there is a strong wind. There are clusters of mutually supporting concepts that I can split off into separate papers, but I have a few unique ways to divide these concepts into clusters. I suspect that any of these individual clusters will be less stable and robust that all of the concepts built into a single paper, but maybe I am just being a paranoid perfectionist.
How can I frame my dilemma to help me make this decision? What question should I ask myself to find the right balance?