# Confidence/Uncertainty

**Confidence**

The mathematically derived statistical estimate indicating how sure the measuring system is that the wireless Phase 2 location data estimate is accurate, within the bounds defined by the Uncertainty value. This is expressed as a percentage, such as 90%, or 45% etc. The specific value is not representative of the accuracy of the PDE locating system.

**Uncertainty**

The mathematically derived statistical estimate, expressed in meters, indicating the size of the area used in the calculation of Confidence. The specific value IS NOT representative of the accuracy of the PDE locating system.

NOTE: Because of the differences in the way that location vendors have implemented their technologies, the resulting Confidence & Uncertainty values cannot be viewed consistently across multiple carriers. Example (not indicative of any particular company):

- Wireless Service Provider “A” sends the following C&U 90%, 115 meters
- Wireless Service Provider “B” sends the following C&U 80%, 115 meters

**Relevant NENA Documents**

*Note: To find and download the document, copy the document number (like NENA-STA-010) from below and search the NENA Standards and Documents page.*

**NENA-STA-010**, NENA i3 Standard for Next Generation 9-1-1**NENA-STA-015**, NENA Standard Data Formats for 9-1-1 Data Exchange & GIS Mapping