Quality & Quantity

, Volume 48, Issue 1, pp 387-408

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Beyond the existence proof: ontological conditions, epistemological implications, and in-depth interview research

  • Samuel R. LucasAffiliated withDepartment of Sociology, University of California-Berkeley Email author 


In-depth interviewing is a promising method. Alas, traditional in-depth interview sample designs prohibit generalizing. Yet, after acknowledging this limitation, in-depth interview studies generalize anyway. Generalization appears unavoidable; thus, sample design must be grounded in plausible ontological and epistemological assumptions that enable generalization. Many in-depth interviewers reject such designs. The paper demonstrates that traditional sampling for in-depth interview studies is indefensible given plausible ontological conditions, and engages the epistemological claims that purportedly justify traditional sampling. The paper finds that the promise of in-depth interviewing will go unrealized unless interviewers adopt ontologically plausible sample designs. Otherwise, in-depth interviewing can only provide existence proofs, at best.


Ontology Epistemology In-depth interviewing Sampling Probability sampling Non-probability sampling Snowball sampling Purposive sampling Theoretical sampling