On the value of R = ΓhΓl at LEP

We show that the present experimental LEP average R = ΓhΓl = 20.795 ± 0.040 is not unambiguous due to the presence of substantial systematic effects which cannot be interpreted within gaussian statistics. We find by Monte Carlo simulation that the C.L. of the original LEP sample is only 3.8 · 10−4. We suggest that a reliable estimate of the true R-value is 20.60 < R < 20.98 which produces only a very poor determination of the strong coupling constant at the Z mass scale, 0.10 < αs(Mz) < 0.15.