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We
live in a very complex world! In order to understand, manage and
analyze our world, we try to simplify it using only the data and
information required. For example, we may want to examine roads
and traffic flows for transportation analysis, or examine remnant
vegetation and national reserve areas in land use planning. Given
the enormous range of objects and factors on the earth to be examined,
this task can be quite often overwhelming.
When examining and exploring aspects of our earth, we will tend
to focus on one or more groups of objects or features (ie.a population)
such as roads, remnant vegetation, people and minerals.
Gathering
data and information about our earth means obtaining data for a
population. It is often not possible or feasible to gather data
about every object in the population, hence we must narrow our data
collection to a subset of the population. This process is referred
to as data sampling.
A sample is a subset of entities
or observations in a target population. It is intended to be representative
of that population. The relationship between the samples and their
parent populations underpins the theory and practice of inferential
statistics. When a statistic is calculated and obtained for that
sample, it is an estimate of the population. Sampling that is based
on spatial properties (ie. geographic location) is referred
to as spatial sampling.
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