Why are my case quality scores low?
Case data quality scores rate the geometries and metadata for a given case based on the clarity of geographic description, conformance between entered geometry and actual area of study sites, and provenance (i.e., reliability) of case contributor in relation to case source. The full rubric for case data quality scores is here.
Common causes of low case quality scores and how to improve them.
- Geographic entity is undefined. The default geographic entity is ‘unknown’. The geographic entity can be specified by choosing an option from a pull-down menu during the ‘metadata interview’ process of case creation. Without specifying a geographic entity, it is difficult to judge whether the geometry that was entered is an appropriate representation of the study site. Not entering a geographic entity will result in a clarity score and overall quality score of “0.” Make sure to add a geographic entity to your case.
- Site area is not specified. The default site are is zero. The site area should be specified as the intended spatial extent of the study site, which is then compared to the area of the study site geometry as calculated in GLOBE. Site area is the primary metric for calculating case geometry conformance with the intended study site area. The only geometry for which a site area is zero is a point geometry. If a case is not a point geometry and the site area is zero, the case will receive a conformance score and overall quality score of “1.” Make sure to specify the site area of your case.
- Polyline was used rather than polygon. If the “Map Draw” feature was used to enter the case geometry, check to see whether the ‘polyline’ or ‘polygon’ tool was used. A polyline will generate an outline of a polygon, but the geometry will have an area equal to zero. This will introduce an error into the case geometry conformance if the intended study site area is non-zero and result in a conformance score of “0″ and overall quality score of “0.” Make sure to enter a polygon, not a line (use the ‘polygon’ tool for drawing site geometries) if they represent a spatially-explicit area, not a line.
- Scale mismatch between the site area reported by the user and the geographic extent of the case study site in GLOBE. If there is a difference in one or more levels of GLOBE spatial scales (landscape versus small region, etc.) then the conformance score of the case will be “1″ and the overall quality score will be “1.” Make sure to accurately enter a case’s geographic extent and site area to avoid a spatial scale mismatch. NOTE: The CLASSIC ERROR is to represent a large area, such as a province, or region using a single geographic point. While this is appropriate for point samples (eg. soil samples) and smaller study sites (<< 100 km2 / 1 GLU), such as field plots and archaeological sites, it is always best to specify and map a more precise geometry, such as a polygon, corresponding to the extent of the geographic entity of the study site, for which the data are provided in the case.