The choice of sources of data and data collection (what to consider as data or not) are influenced by the experience and culture of the researcher. the extent to which the researcher belongs to the study context also affect the data analysis and interpretation. Not only that. Generally, it is more helpful to discuss about the degree of objectivity of a researcher rather that aiming at an "objective" researcher.
At least we have tried to do what You are looking for - at some of the articles in Lithuanian language on Sweden and to the one in English language about 30 years ago assasinated Swedish prime-minister and Socialdemocratic party leader - Olof Palme:
Article Improvement of Public Governance by Olof Palme and h is Hist...
I dont think being abstract has to do with data collection. The researcher is more likely to do his, or her work dependently on the course of the study. It would be nice to look at the definition of historiography- The Study of Historical Writing.