Data Methods

Learn more about the data that informs AHEAD.

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Knowledge of HIV Status indicator icon Knowledge of HIV Status

Knowledge (or awareness) of HIV-positive status means a person is tested and diagnosed with HIV. Knowledge of HIV status is estimated as the percentage of persons with HIV who have received a diagnosis and is calculated by dividing the estimated number of persons living with diagnosed infections by the estimated total HIV prevalence (diagnosed and undiagnosed cases) for each year. The estimated number of diagnoses and prevalence are derived from HIV surveillance data reported to CDC from 50 states, the District of Columbia, and Puerto Rico for persons aged ≥ 13 years. For more specific information about how knowledge of status is calculated, please refer to the CDC’s HIV Surveillance Report:

Formula for the Knowledge of Status indicator


Completeness of reporting varies among states and local jurisdictions. Estimates should be interpreted with caution for EHE areas (including Phase 1 EHE states, EHE jurisdictions, or states that contain EHE jurisdictions) that do not have laws requiring complete reporting of laboratory data or have incomplete reporting.

  • EHE areas without laws requiring complete reporting:
    • Idaho
    • New Jersey
  • EHE areas with incomplete reporting:
    • Kansas
    • Kentucky
    • Pennsylvania (excluding Philadelphia)
    • Vermont
    • Puerto Rico

Estimates should also be interpreted with caution for EHE areas (including Phase 1 EHE states, EHE jurisdictions, or states that contain EHE jurisdictions) with incomplete ascertainment of deaths. Areas with incomplete ascertainment of deaths in 2019 were Kansas, Massachusetts, Mississippi, Nevada, North Dakota, and Vermont.

Relative Standard Error (RSE)

The relative standard error RSE is a measure that shows how large the standard error is relative to the size of the estimated value. It is calculated by dividing the standard error of an estimated value by the estimated value itself, and then multiplied by 100 and expressed as a %. Smaller RSEs are indicative of more reliable results, and larger RSEs indicative of less reliable results.

Estimates with a relative standard error (RSE) of ≥30% do not meet the standard of reliability and are represented in the following way:

  • Estimates with an RSE of 30% - 50% are marked with an asterisk (*), indicating that they should be used with caution.
  • Estimates with an RSE>50 percent are not shown, and are replaced with the phrase “Data N/A due to high relative standard error.”

To reflect model uncertainty, all estimates were rounded to the nearest 100 for estimates of more than 1,000 and to the nearest 10 for estimates of less than 1,000.

More information can be found at: HIV Surveillance Report Supplemental Report Volume 26, Number 1.