the region of interest. The subregions are sampling units defined on
maps or other cartographic materials.
Area sample
The units selected for measurements from an area frame.
Arid ecosystems
Terrestrial systems characterized by a climate regime where the
potential evapotranspiration exceeds precipitation, annual precipitation is not less than 5 cm and not more than 60 cm, and daily and
seasonal temperatures range from 40
C to 50
C. The vegetation is
dominated by woody perennials, succulents, and drought-resistant
trees.
Assessment
Interpretation and evaluation of EMAP results for the purpose of
answering policy-relevant questions about ecological resources,
including (1) determination of the fraction of the population that
meets a socially defined value and (2) association among indicators
of ecological condition and stressors.
Assessment endpoint
Formal expressions of the actual environmental value that is to be
protected. Risk Assessment Forum defines this as an explicit
expression of the environmental value that is to be protected.
Operationally in EMAP, an assessment endpoint is the range, proportion, or percentage of a resource that is known with statistical
confidence to be in a specified condition.
Association rule
A rule that unambiguously links a single resource sampling unit
with a grid point. Several association rules have been identified in
selecting a Tier 2 sample via the EMAP grid.
Attribute
Any property, quality, or characteristic of sampling unit. The indicators and other measures used to characterize a sampling site or
resource unit are representations of the attributes of that unit or site.
A characteristic of a map feature (point, line, or polygon) described
by numbers or text; for example, attributes of a tree, represented by
a point, might include height and species.
Augmented sample
A grid-based sample whose size has been increased by using a
denser grid.
Auxiliary data
Data derived from a source other than EMAP, that is, from an
experiment or from another monitoring or sampling program, either
federal or state. The sampling methods and quality assurance protocols of auxiliary data must be evaluated before the data are used. It
is always important to establish the population represented by
auxiliary data.
Azimuthal map projection One of a class of map projections formed by projecting coordinates
from the earth’s surface directly onto a plane that is either tangent at
a point on the surface or that intersects the surface in a circle. When
the plane intersects the surface, the projection is said to be the
secant case.
Baseline grid
The fixed position of the EMAP grid as established by the position
of the hexagon overlaying the United States. This is distinguished
from the sampling grid, which is shifted a random direction and
distance from the baseline grid.
Bias
In a sampling context, the difference between the conceptual
weighted average value of an estimator over all possible samples
and the true value of the quantity being estimated. An estimator is
said to be unbiased if that difference is zero. The systematic or
persistent distortion of a measurement process which deprives the
result of representativeness. (i.e., the expected sample measurement
is different than the sample’s true value).
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maps or other cartographic materials.
Area sample
The units selected for measurements from an area frame.
Arid ecosystems
Terrestrial systems characterized by a climate regime where the
potential evapotranspiration exceeds precipitation, annual precipitation is not less than 5 cm and not more than 60 cm, and daily and
seasonal temperatures range from 40
C to 50
C. The vegetation is
dominated by woody perennials, succulents, and drought-resistant
trees.
Assessment
Interpretation and evaluation of EMAP results for the purpose of
answering policy-relevant questions about ecological resources,
including (1) determination of the fraction of the population that
meets a socially defined value and (2) association among indicators
of ecological condition and stressors.
Assessment endpoint
Formal expressions of the actual environmental value that is to be
protected. Risk Assessment Forum defines this as an explicit
expression of the environmental value that is to be protected.
Operationally in EMAP, an assessment endpoint is the range, proportion, or percentage of a resource that is known with statistical
confidence to be in a specified condition.
Association rule
A rule that unambiguously links a single resource sampling unit
with a grid point. Several association rules have been identified in
selecting a Tier 2 sample via the EMAP grid.
Attribute
Any property, quality, or characteristic of sampling unit. The indicators and other measures used to characterize a sampling site or
resource unit are representations of the attributes of that unit or site.
A characteristic of a map feature (point, line, or polygon) described
by numbers or text; for example, attributes of a tree, represented by
a point, might include height and species.
Augmented sample
A grid-based sample whose size has been increased by using a
denser grid.
Auxiliary data
Data derived from a source other than EMAP, that is, from an
experiment or from another monitoring or sampling program, either
federal or state. The sampling methods and quality assurance protocols of auxiliary data must be evaluated before the data are used. It
is always important to establish the population represented by
auxiliary data.
Azimuthal map projection One of a class of map projections formed by projecting coordinates
from the earth’s surface directly onto a plane that is either tangent at
a point on the surface or that intersects the surface in a circle. When
the plane intersects the surface, the projection is said to be the
secant case.
Baseline grid
The fixed position of the EMAP grid as established by the position
of the hexagon overlaying the United States. This is distinguished
from the sampling grid, which is shifted a random direction and
distance from the baseline grid.
Bias
In a sampling context, the difference between the conceptual
weighted average value of an estimator over all possible samples
and the true value of the quantity being estimated. An estimator is
said to be unbiased if that difference is zero. The systematic or
persistent distortion of a measurement process which deprives the
result of representativeness. (i.e., the expected sample measurement
is different than the sample’s true value).
218
S. O. Darkwah et al.