Significant digits for HepData table

This page documents the guidance of determining the significant digits for data tables uploaded to HepData

- Choose the smaller one between statistical and systematic uncertainties when both are reported. Otherwise, use the single error reported.

- Follow PDG practice: "The basic rule states that if the three highest order digits of the error lie between 100 and 354, we round to two significant digits. If they lie between 355 and 949, we round to one significant digit. Finally, if they lie between 950 and 999, we round up to 1000 and keep two significant digits. In all cases, the central values is given a precision the matches that of the error"
  • PRD 98 (2018) 030001, Introduction 5.3
- Examples:
  • 0.279008 +/- 0.0123261 +/- 0.000766099 -> 0.2790 +/- 0.012 +/- 0.0008  (significant digits determined based on 0.000766099)
  • 0.279008 +/- 0.0123261 +/- 0.0766099     -> 0.279 +/- 0.012 +/- 0.08  (significant digits determined based on 0.0123261)
- An example code to format the input values, following PDG suggestions, can be found here:
  • The formatting code is updated on Mar. 15th 2021, based on improvement introduced by Patrick John Steffanic and Christine Nattrass
  • Instructions are included in the zip file
  • Github link for the source file:
-Special cases of including more significant digits than recommended will be treated on a case-by-case basis by GPC chair and PAC.