Conceptual
Framework
This paper shall
utilize the mathematical modelling by Arbia, G., Griffith, D.
and Haining, R. (1999).
The purpose of adopting this approach using maps and error processes with
simple but well-defined properties is to understand better how different
elements of the situation, individually and together, contribute to the final
propagated error. The problem with using real maps (rather than artificially
generated maps) is that real maps usually have complex structures so that it
may not be clear the extent to which aggregate statistics computed to measure
the severity of the error problem are an aggregation across many types of quite
different map segments with different structures. Usually, real errors are not
known for any data set, and unless their structure is uniform across the map,
the same problem for interpreting aggregate statistics could arise.
Using formal
mathematical modeling, rather than just simulation, means that where
theoretical results can be obtained they can be used to check simulation output
before the simulation is used to obtain properties that are not accessible to
mathematical analysis. Furthermore it is only through formal mathematical
modeling, leading to closed-form expressions, that a rigorous study can be
undertaken that yields quantitative and qualitative insights as to how
different elements contribute individually or interactively to error
propagation. The formal expressions make the contributions explicit, and regression
(adding maps) and ANOVA (ratioing) are used to quantify the relative
contributions of each term in the expression. Where theoretical results have
not been obtained, as in the case of ratioing, simulation alone, even with
regression analysis of the outputs cannot produce the same quality of evidence
because of the dangers of model misspecification in using regression.
(Arbia, G., Griffith, D. and Haining, R., 1999)
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