---
kind: "section"
citation: "40 C.F.R. § 1090.1805"
title: "40"
number: "1090.1805"
heading: "Representative samples."
url: "https://uscodex.org/cfr/40/1090.1805"
---

# §1090.1805. Representative samples.

- (a) If the specified procedures require evaluation of a representative sample from the overall population for a given data set, determine the number of results for evaluation using one of the following methods:
  - (1) **Determine sample size using the following table—**
  - (2) Determine sample size corresponding to a confidence level of 95 percent, an expected error rate of 0 percent, and a maximum tolerable error rate of 10 percent, using conventional statistical principles and methods.
  - (3) Determine sample size using an alternate method that is equivalent to or better than the methods specified in paragraphs [(a)(1)](#a-1) and [(2)](#a-2) of this section with respect to strength of inference and freedom from bias. An auditor that determines a sample size using an alternate method must describe and justify the alternate method in the attestation engagement report.
- (b) Select specific data points for evaluation over the course of the compliance period in a way that leads to a simple random sample that properly represents the overall population for the data set.

## Notes

### Amendments

[85 FR 78469, Dec. 4, 2020, as amended at 90 FR 4367, Jan. 15, 2025]

### Authority

Authority: 42 U.S.C. 7414, 7521, 7522-7525, 7541, 7542, 7543, 7545, 7547, 7550, and 7601.

### Source

Source: 85 FR 78469, Dec. 4, 2020, unless otherwise noted.

### Amendments

[85 FR 78469, Dec. 4, 2020, as amended at 90 FR 4367, Jan. 15, 2025]