A Privacy-Preserving Method for Longitudinal Participant Linkage in Web Surveys
DOI:
https://doi.org/10.29015/cerem.1043Keywords:
longitudinal survey methodology, anonymous respondent linkage, self-generated identification codes (SGIC), data privacy in empirical researchAbstract
Aim: To enable longitudinal linkage in online panel surveys without collecting direct identifiers and while aligning with modern data-protection requirements
Design / Research methods: The article proposes a client-side protocol where participants create a reproducible secret from a self-chosen pseudonym and an ordered image sequence. The browser normalizes and cryptographically hashes these inputs to derive a short alphanumeric core code, adds a modulus-97 checksum for strict local validation, and the backend stores only a salted hash scoped to a specific study (form-family) context.
Conclusions / findings: This paper introduces a client-side protocol for generating anonymous yet linkable participant identifiers in web-based surveys by deriving a reproducible code from a user-chosen pseudonym and image sequence entirely in the browser, and by storing only a form-family–salted hash on the server for longitudinal linkage within a study. The design incorporates a checksum for strict client-side validation and is intended to reduce spurious identifiers caused by typographical errors; empirical validation of matching performance, usability, and security properties is left for future work.
Originality / value of the article: The work refines SGIC-style respondent-generated linkage by combining graphical secrets with browser-based cryptographic processing, checksum-based client-side validation, and form-family salting-yielding a concrete, implementable algorithm that improves privacy-respecting longitudinal linkage.
JEL: C81, C83.
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