Chapter 6. Uncertainty

1. Why are geographic data imperfect?
2. What is measurement error?
3. What is the definition of accuracy?
4. Spatial data are unique in that they often don't have natural units, a natural spatial extent, or a natural scale.  Explain.
5. Zone boundaries are often vague best guesses.  Explain.
6. What are indirect and direct indicators and why does using them make your spatial database ambiguous?
7. The unit of analysis is an important consideration when measuring relationships between phenomena.  Why?
8. What is a region and how can a GIS help define one?
9. Compare how might you show uncertainty of a coastline in the vector and raster models.
10. What is a mixel and what does spatial resolution have to do with the percentage of mixels if there is a constant group of classes?
11. Uniform zones are created in the vector system to preserve confidentiality and limit data volume.  Explain each.
12. Zones are usually not randomly located.  They are chosen based on pragmatic reasons.  What are some examples of these pragmatic reasons?
13. What are legacy data?
14. What are overshoots, undershoots, dangles, sliver polygons, and how are they caused?
15. What is rubber-sheeting and what does it have to do with edge matching?
16. GPS is an absolute vector measurement device and has burst the data capture bubble.  Explain.
17. Conflation combines the information from two data sources into a single source.  Datasets with different lineages often reveal unsuspected errors when overlaid.  Give an example.
18. Differences in definitions are a major impediment to integration of geographic data, such as wetlands, over wide areas. Explain.
19. Uncertainties in data lead to uncertainties in the results of analysis.  What would you say to a critic of GIS in response to this concern?
20. What is the ecological fallacy?
21. What is the modifiable areal unit problem?
22. Understanding that the MAUP exists is in itself important.  However, Openshaw's geocomputational approach deals with the problem with computational power.  Explain the concept behind his approach.