We have discussed a range of factors that that introduce uncertainty into measurements. e.g. resolution of the instrument, technique used, uncertainty in establishing reference points and variability in the quantity being measured etc. In practice it is often the case that some of these factors are negligible compare to others.
E.g. If you were to use a ruler with a millimetre scale to measure the length of a precision manufactured component that had very smooth and level edges you may find that all other sources of uncertainty are negligible compared to that due to the resolution of the ruler. When taking any measurement it is important to identify which factors need to be considered when determining precision and accuracy and which ones are negligable.
The following section shows just a few examples of analysing a measurement activity and applying techniques to help take the most precise and accurate measurements.