A topic in research methodology
Interview data is usually collected as an audio recording of the talk. Video recording may also sometimes be used. In some circumstances, recording devices cannot be used, and notes are taken instead. Due to the limitations of note taking, this is not usually used where recording is possible (and should be justified as a research choice in any report of the research).
Interview data is usually converted into transcripts of the recordings – a verbatim report of the conversation showing who said what. In some kinds of research the transcripts may also include such features as length of pauses, speech inflections (changes in pitch and tone) and accompanying gestures.
There is no such thing as a perfect transcription, as decisions about what to include, and how to represent spoken language in a written text have to be made (e.g. how should a mispronounced word be recorded?) Decisions about how to transcribe will depend upon the kind of data analysis needed to answer research questions in a particular study. [Read about transcription conventions.]
[Extracts from transcripts of research interviews are included in many of the posts on this site.]
My introduction to educational research:
Taber, K. S. (2013). Classroom-based Research and Evidence-based Practice: An introduction (2nd ed.). London: Sage.