Citation(s) from the GunPolicy.org literature library
CDC. 2014 ‘Questions About Death Rates - Data Unreliable.’ CDC WONDER Online Database - Underlying Cause of Death, Results. Atlanta, GA: Centers for Disease Control and Prevention / CDC, National Center for Health Statistics. 5 January
Relevant contents
1) Questions About Death Rates - Data Unreliable
g) Why are death rates sometimes flagged as "Unreliable" or "Suppressed"?
Death rates based on counts of less than twenty… are flagged as "Unreliable". A death rate based on fewer than 20 deaths has a relative standard error (RSE(R)) of 23 percent or more. A RES(R) of 23 percent is considered statistically unreliable.
Death counts and death rates are "Suppressed" when the data meets the criteria for confidentiality constraints. See Assurance of Confidentiality for more information.1
Last accessed at:
http://wonder.cdc.gov/wonder/help/ucd.html#Unreliable