AbstractThe meaning and purpose of sampling are discussed. Results are presented from a series of road trials on the sampling of asphalt mixtures to demonstrate the importance of bias and variability introduced into test measurements by sampling. Further variability is introduced by the reduction in size by quartering of gross samples to the size required for testing; it is shown that this variability is reduced when a riffling technique is used. It is usual to adjust the measured binder and filler contents of asphalt for the disturbance caused by sampling. Evidence is presented to show that the adjustments in current use may not be well chosen and some more appropriate factors are suggested.