How can I decide which estimates are unreliable due to small sample size or other factors?

This Statistical Inference Report outlines procedures for identifying unreliable estimates. Chapter 9 explains these procedures, and they are summarized in Table 9.1 (pg. 66). Estimates that do not meet the criteria in the guidelines should not be reported or used. Sample codes for identifying unreliable output in SUDAAN®, Stata®, SAS®, R, and SPSS® are available in Appendix A (Exhibits A.2.3, A.3.3, A.4.3, A.5.3, and A.6.3, respectively).

A shorter explanation is also available in the annual Methodological Summary and Definitions (MSD), chapter 3.2.