How to refer to myself as a subject of study in a research paper? Okay so I have collected personal spending data of myself and significant other over a period of 6 months. I'm quite happy with the data and would like to present it and write it up as a research paper. I'm not going to be publishing it but would like to do it for fun (and a bit of practice can't hurt).

The dilemma I am facing at the moment is that I cannot figure out how to refer to myself or my significant other as participants in the study. I have been trying to figure this out for a few days now and google is really giving me a hard time. I cannot find a single thing relevant to what I am trying to do.

My first issue I have come to is that I am captioning a figure that reads similar to this. Figure 1: Average daily spending vs time for myself (solid line) and significant other (dotted line).

Is this the correct way to refer to myself and significant other? It feels much too informal for my liking. I have considered making a small statement that states that myself will be referred to as "participant A" and my significant other will be referred to as "participant B", but this might add unnecessary confusion.

Is there a standard on this? This has been driving me absolutely crazy over the past few days and would really appreciate any insight or suggestions.
Use the names "Participant 1" and "Participant 2" in figure captions and throughout the text. You can then, if you want, explain at one point, who these participants are (if it actually matters), but at least you don't have to repeatedly refer to yourself and your s.o..