Self-tracking as knowledge production: Quantified self between prosumption and citizen science

"Self knowledge through numbers" is the slogan of the growing international Quantified Self movement. This paper deals with the question what kind of knowledge is actually being acquired here and how this knowledge production is to be characterized. It shows that the knowledge production of self-trackers can be positioned in-between prosumption, on the one hand, and citizen science on the other. A typology of self-tracking activities is presented, the main focus being particularly on those that resemble research. These research activities of self-trackers are termed personal science since they attempt to produce verified knowledge using scientific methods and according to scientific criteria, although their object is the researcher him/herself and their goal is practical knowledge for the person's self-use.