GEOG 328 Definitions Flashcards
Inverse Distance Weighted (IDW)
Inverse distance weighted (IDW) interpolation is an exact method that enforces
that the estimated value of a point is influenced more by nearby known points
than those farther away.
Trend Surface Analysis
A global polynomial interpolation that fits a smooth surface defined by a mathematical function (a polynomial) to the input sample points
Kriging
An interpolation technique that uses regionalized variable theory to
incorporate information about the stochastic aspects of spatial variation
when estimating interpolation weights.
Semivariance
A measure of the degree of spatial dependence between samples at a specific point.
Semivariogram (Hint: 2 types)
The experimental Semivariogram provides a description of how the
data are related (correlated) with distance.
An empirical Semivariogram is a smooth function defined by a model
equals that represents the experimental Semivariogram.
Spatial Analysis
A subset of analytic techniques whose results depend on the spatial frame, or will change if the frame changes, or if objects are repositioned within it (Goodchild and Longley, 1999).
Location
Describes where a “thing” is in space.
Attribute
Provides information about the “thing”.
Vector Data Model
Uses points, lines, polygons to represent
spatial features or objects with a clear
spatial location and boundary
Raster Data Model
Uses a grid to grid cell to represent a
continuous field e.g. elevation, temperature.
Spatial Data
Data which are a representation of our behavior,
indicative of an underlying process which governs
the pattern.
Spatial Pattern
Spatial pattern = spatial distribution of objects.
Spatial patterns are a realization of a spatial process
e.g. locations of people infected with West Nile virus
Spatial Process
Spatial process = a spatial phenomena that results in a spatial pattern
e.g. mosquito infection and transmission.
Ecological Fallacy
The belief that relationships observed for groups necessarily hold true for individuals.
e.g. If countries with more fat in the diet have higher rates of breast cancer, then women who eat fatty foods must be more likely to get breast cancer.
Model
A model is a simplified representation of a phenomenon or a system
Multi-criteria Model
A model of the real world, incorporating spatial data and relationships,
used to aid understanding of spatial form and process
Binary Model
A Binary model uses a boolean output to present explicit data which denotes either suitable/unsuitable outputs.
Interpolation
The process of estimating (predicting) values at unsampled sites within an area for which there exist some sampled (point) observations.
Deterministic Model
Deterministic techniques are based on surrounding measurements (mathematical functions) to calculate the surface. Does not use any probability theory.
e.g. Thiessen polygons, IDW and spline interpolation.
Stochastic Model
Stochastic techniques use both mathematical and statistical functions for prediction. They incorporate the concept of randomness: the interpolated surface is conceptualized as one of many that might have been observed, all of which could have produced the known data points
e.g. Polynomial regression and kriging are stochastic interpolation methods.
Global Interpolator
A global interpolator derives a surface model using all of the available data to
provide predictions for the whole area of interest by applying a single function
across the entire region.
Local Interpolator
A local interpolator calculates predictions from the measured points within neighbourhoods or smaller spatial areas within a larger study area to ensure that interpolated values are determined only by nearby points.
Exact Interpolation
Exact interpolation honours the data points upon which the interpolation is based
so that the interpolated surface passes through all points whose values are known.
Approximate Interpolation
Approximate interpolation is used when there is uncertainty in the given surface values. In
many data sets there are global trends and local variation that produces
uncertainty (error) in the sample values.
