Monday, November 2, 2015

Analysis of non spatial attribute data

Non-spatial data or attribute data is that data that is independent of all location considerations.

The analysis module usually contain four important functions:
1. Selection is a simple operation, but it is important because all subsequent work is based on the results of the selection process.
2. Manipulation has to do with aggregation, buffering, overlaying and interpolation.
3. Exploration is the first step in discovering any kind of pattern or cluster in a data set. Explorative spatial data analysis (ESDA) uses the data in an inductive way to get new insight about spatial patterns and relations - Spatial statistics such as Moran's I and the G statistics are important tools in explorative spatial data analysis.
4. Confirmation is a set of tools for estimation of process models, simulation and forecasting.

Analysis in GIS is different from other statistical analysis since the attribute data establishes links to maps for visual analysis. Before starting any analysis, the problem should be assessed and an an objective should be established The following steps outline the basic procedure for geographical analysis:

  1. Establish the objectives and criteria for the analysis. Define the problem and then identify a sequence of operations to produce meaningful results. 
  2. Prepare the data for spatial operations. Prepare all map coverages for the proposed data analysis. Add one or more attributes to coverages in the database if necessary. 
  3. Perform the spatial operations and combine the coverages, e.g. creating buffering zones around features, manipulating spatial features and performing polygon overlay. 
  4. Prepare the derived data for tabular analysis and ensure the feature attribute table contains all the items needed to hold the new values to be created. 
  5. Perform the tabular analysis. Calculate and query the relational database using the model defined in the first step.
  6. Evaluate and interpret the results. Examine the results and determine whether the answers are valid. Simple map displays and reports can help in this evaluation
  7. Refine the analysis if needed and repeat the analysis.