The topic of my paper is the uncertain fields which PhD students have to face during their research, especially using biographies. The paper is based on the oral communication «Sample, Distance and Analytical Choices», Bedingungen und Prozesse der Einsozialisation in die Biographieforschung, Fachhochschule Frankfurt/M, Fachbereich Soziale Arbeit und Gesundheit, 4- 5 December 2009. It has been published in the Rundbrief of the German Sociological Association, Section Biographies