Discuss the types of data uncertainty that may be encountere

Solution

GIS software can make the users to think that their data is accurate and precise to a degree that is not quite real. Scale, for example, is an inherent error in cartography; depending on the scale used, we will be able to represent different type of data, in a different quantity and with a different quality. Cartographers should always adapt the scale of work to the level of detail needed in their projects.

The age of data may be another obvious source of error. When data sources are too old, some, or a big part, of the information base may have changed. GIS users should always be mindful when using old data and the lack of currency to that data before using it for contemporary analysis.

There are some types of errors created when formatting data for processing. Changes in scale, reprojections, import/export from raster to vector, etc. are all examples of possible sources of formatting errors.

Other sources of error may not be so obvious, some of them originated at the moment of initial measurements, even from the moment of capturing the data cause by users.

Quite often we can identify quantitative and qualitative errors. A common mistake consists on label errors. For instance, an agricultural land may be incorrectly marked as a marsh, and this would cause an error that the map user may not notice because he may not be familiar with the area in question. Quantitative errors may occur also when using instrument that have not been properly calibrated creating subsequent errors hard to identify in the field, but that will cause your project to lose accuracy and reliability.

Error factor involves assessing both the imprecision of data and its inaccuracies.