Instrument Performance Characteristics » Precision and Resolution » Definitions of “Resolution”
There are several components to a description of resolution, and in practice the term is often applied to these individual components as well as to their net result. The components include:
- The smallest difference between measurands that will lead to corresponding measurements indicating that the measurands are different. The desired indication will have an associated confidence level, often 68.3% or that corresponding to one standard deviation. A primary factor influencing this aspect of resolution is the precision of the instrument.
- The smallest change in the indicator (e.g., meter or digital display) that can be perceived. For example, the instrument resolution may be limited by the ability of an operator to read an analog display, by hysteresis in that display, or by the smallest incremental change reported on a digital display. In the case of a digitized result, the resolution is limited by the change corresponding to one unit in the digitized output.
- For a spectrometer, the smallest difference in frequency that can be resolved.
- For a time series, the temporal resolution is the increment between consecutive measurements, although if a particular sensor responds more slowly than this, the temporal resolution of that sensor may be lower.
Let’s consider definitions #1 and #2 in more detail. (Definitions #3 and #4 are specific to instrument types or to the data series and are largely self-explanatory in their definitions.)