At BESIII, the R value is measured with a total of 14 data points with the
corresponding c.m. energy going from 2.2324 to 3.6710 GeV.
The statistical uncertainty of the measured R is less than 0.6%. Two different
simulation models, the LUARLW and a new Hybrid generated, are used and give
consistent detection efficiencies and initial-state-radiation corrections. An
accuracy of better than 2.6% below 3.1 GeV and 3.0% above is achieved in the R