The Need for Standardized Evidence Sampling in CMMC Assessments: A Survey-Based Analysis of Assessor Practices

TL;DR

This study highlights the variability in evidence sampling practices in CMMC assessments due to lack of standardized guidance, emphasizing the need for a risk-informed, flexible sampling framework to improve assessment consistency.

Contribution

It provides empirical evidence from a survey showing the inconsistency in sampling practices and advocates for developing standardized, risk-based sampling guidelines in CMMC assessments.

Findings

Sampling practices are mainly driven by assessor judgment and perceived risk.

Inconsistencies across assessments are common due to lack of formal standards.

Participants support standardized guidance but oppose rigid percentage rules.

Abstract

The Cybersecurity Maturity Model Certification (CMMC) framework provides a common standard for protecting sensitive unclassified information in defense contracting. While CMMC defines assessment objectives and control requirements, limited formal guidance exists regarding evidence sampling, the process by which assessors select, review, and validate artifacts to substantiate compliance. Analyzing data collected through an anonymous survey of CMMC-certified assessors and lead assessors, this exploratory study investigates whether inconsistencies in evidence sampling practices exist within the CMMC assessment ecosystem and evaluates the need for a risk-informed standardized sampling methodology. Across 17 usable survey responses, results indicate that evidence sampling practices are predominantly driven by assessor judgment, perceived risk, and environmental complexity rather than formalized standards, with formal statistical sampling models rarely referenced. Participants frequently reported inconsistencies across assessments and expressed broad support for the development of standardized guidance, while generally opposing rigid percentage-based requirements. The findings support the conclusion that the absence of a uniform evidence sampling framework introduces variability that may affect assessment reliability and confidence in certification outcomes. Recommendations are provided to inform future CMMC assessment methodology development and further empirical research.