How to Anonymize Interview Transcripts

When you interview people for a thesis or research project, you are usually responsible for protecting their identity. Before you share transcripts with your advisor, quote them in your thesis or archive them, you should remove or replace information that could identify your participants. This guide explains why anonymization matters, what to replace and how to work consistently.

Note: This guide provides general information and is not legal advice. The rules that apply to you depend on your institution, your consent forms and your country. If you have questions, ask your Institutional Review Board (IRB), your ethics committee or your advisor.

Why anonymization is necessary

Most research involving people requires approval from an IRB or ethics committee. As part of that process, you usually tell participants how their data will be handled, and you describe this in your consent form. Anonymizing transcripts is one of the main ways to keep that promise.

It also helps to understand two related terms. The University of Bath Library describes de-identification as the "removal of explicit identifiers" and anonymization as a state in which "identification is impossible" (source). It adds that "De-identified transcripts may still contain indirect identifiers and should be treated more carefully depending on the potential for harm."

Full anonymization is not always achievable. KU Leuven's research data management guidance notes: "It is not always possible to fully anonymise interview transcripts, and anonymisation can also impact on the usefulness of data because certain information is removed" (source). For this reason, it is wise to combine careful anonymization with secure storage and limited access.

What needs to be replaced

Direct identifiers are the obvious ones:

Names of participants and of other people they mention
Email addresses, phone numbers and street addresses
Usernames and social media handles

Indirect identifiers are easier to miss, because each detail may seem harmless on its own. In combination, they can still point to a specific person:

Places such as towns, schools, clinics or neighborhoods
Employers, organizations and job titles
Exact dates, such as a birthday or the date of a specific event
Unusual life events, rare conditions or distinctive roles
Details about family members

Ask yourself whether someone who knows the participant, such as a colleague or a neighbor, could recognize them from the transcript. If the answer could be yes, replace or generalize the detail.

Use placeholders consistently

Replace identifying details with clear placeholders in square brackets, so readers can see that something was changed. For example:

"Maria" becomes [Participant 2] or a pseudonym such as [Anna]
"Riverside Hospital" becomes [Hospital A]
"Springfield" becomes [City 1] or a general description such as [small town in the Midwest]
"my boss at Acme Corp" becomes "my boss at [Company B]"

Keep a separate key that lists each placeholder and its original value. Store this key securely and separately from the transcripts, and follow your institution's rules on who may access it and when it must be deleted.

Consistency is essential. If "Hospital A" refers to one hospital in the first interview, it must refer to the same hospital in every other interview. Otherwise, your analysis may become confusing or misleading.

A practical workflow

Anonymize during or right after transcription. You know the context best while the interview is fresh.
Search for names. Use your editor's search function to find every occurrence of each name you know.
Read the full transcript once more. Look specifically for indirect identifiers that a search will not find.
Check quotes before you use them. A short quote in your thesis can be more revealing than the full transcript, because readers focus on it.
Document your approach. Briefly describe in your methods chapter how you anonymized the data.

Checklist before you submit

All names of people are replaced or removed.
Places, organizations and dates are generalized where necessary.
Placeholders are used consistently across all transcripts.
The key linking placeholders to real names is stored separately and securely.
Quotes in your thesis have been checked for indirect identifiers.
Your approach matches what you promised in your consent form and your IRB or ethics application.

How Stillscript can help