6.09 Summary

The resolution of a measuring instrument determines the smallest change in value that it can discriminate between (and therefore quantify). E.g. a 2 digit digital thermometer with a range from 0 to 99^oC cannot show and increase in temperature of less than 1^oC
The resolution of a measuring instrument introduces uncertainty and limits the precision of the measurement. (In the above example the thermometer measurements will produce an uncertainty of +/- 0.5 ^oC)
The precision limit set by an instrument can sometimes be further limited by the measurement technique used. E.g. A stopwatch capable of a resolution of 0.01 seconds will at best achieve an uncertainty of +/- 0.1 seconds when operated manually.
In some situations there are no clear and unique reference points to measure between and the uncertainty in the measurement must reflect this.
When repeated measurements are made variability in the measured property or random errors in the measurement technique can produce different measurement values. The uncertainty must reflect this however statistical techniques can be used to improve (reduce) the uncertainty in the final measurement value.
The statistical techniques can also provide a confidence value which indicates the confidence that the true value does actually lie within the uncertainty interval stated.
When measurements are taken of changing values using electrical or mechanical measuring devices it is important that the mechanism can respond fast enough to reflect the changing value being measured.
In these situations data logging is usually required which involves recording a succession of values quickly enough so that the measured value is stable while each individual reading is recorded.