Thing or subset (real or virtual) which is intended to be representative of a larger thing or set. A sample is created or selected for the purpose of making observations or measurements to determine the value of one or more properties, traits or qualities of the larger thing. The essential property of a sample is the 'is-sample-of' relationship with the larger thing.
A material sample is sometimes known as a specimen, and is typically selected to allow ex-situ observations.
A statistical sample or subset is a specified number of individuals from a population.
A spatio-temporal sample may have the same dimension but a smaller extent than the thing which it represents, or may have a lower topologic dimension than the thing which it represents.
Samples are often related to other samples, either through sub-sampling, or as members of a sequence of siblings, or through specific treatments that transform the original sample into one or more new samples. The nature of the relationship is important, but the complete set of relationships cannot be enumerated as this is an important area of innovation.
Spatio-temporal samples - lower dimensionality
- a point (0-D sample) within a curve (1-D), surface (2-D) or volume (3-D),
- e.g. monitoring station, pixel
- a curve (1-D) within a surface (2-D) or volume (3-D),
- e.g. transect, flightline, cruise track, borehole trace
- a surface (2-D) within a volume (3-D)
- e.g. cross-section
Spatio-temporal samples - same dimensionality
- interval within a curve
- interval within a time-series
- quadrat within a tract
- core from a body of rock.