Table 2. Typical specifications for a 100-1000 L automatic pipette. Inaccuracy Pipette size 100-1000 L Volume L 100 500 1000 Absolute L 3 5 6 %A % 3 1 0.6 Imprecision SD L 0.6 2 2 % CV 0.6 0.4 0.2 Random errors Random errors cause results to vary in an unpredictable way from one measurement to the next. They are caused by chance variations in the measurement process that are outside your control. Random errors are present when any measurement is made but due to their unpredictable nature, they cannot be corrected for. The effect of random errors can be reduced, however, by making more measurements and reporting the mean. The magnitude of the random errors will determine the precision of the measurement results. When using volumetric glassware there will always be slight variations in judging the position of the meniscus relative to the graduation marks, and when using pipettes and burettes there will be small ariations in the actual amount of liquid delivered. These are examples of random