The results are sample-based estimates and therefore subject to differing degrees of sampling variability, i.e. the true value for any measure lies in a range about the estimated value.
Mae'r canlyniadau'n amcangyfrifon sy’n seiliedig ar y sampl, ac o’r herwydd mae gwahanol raddfeydd o amrywioldeb samplu ynghlwm wrthynt, h.y.