Global Variable Summary Statistics
When exploring GLOBE’s Global Variables, a series of “summary statistics” are provided based on the original data (i.e. “native” data) as well as the GLOBE transformed data (i.e. “Globe”). How global variables are transformed and processed for use in GLOBE is documented here. When global datasets are geoprocessed using GLOBE’s foundational Globe Land Units (GLUs), the original data is transformed. GLOBE therefore provides the following summary statistics so researchers may understand the differences between native datasets and these datasets following geoprocessing in GLOBE. In the variable explorer GLOBE also provides hyperlinks to all datasets where global data was originally obtained for reference purposes.
GLOBE’s global variables are also comprised of both native and extrapolated data. When GLOBE’s foundational structure was created, LandScan 2007 population density was used as a land mask to select all Global Land Units (GLUs) that contained land. This created a base extent and resolution (30 arcsec) to which all global variable datasets were converted. If the native extent of a global variable was less than that of LandScan 2007 (typically small islands were not included), and it was appropriate and/or possible to extend the variable (e.g. mean temperature can be extrapolated, whereas world protected areas cannot), then the global variable was extrapolated to include as much land mass as possible. A tiered classification was developed that summarizes the final coverage (i.e. extent) and degree of extrapolation applied to the native data. Click here for more details on this classification system. The global variable summary statistics therefore also include information on the percentage of native, extrapolated, and missing data, where appropriate.
|Native Range||The original range of values from the original dataset prior to geoprocessing in GLOBE. See source hyperlinks for original untransformed datasets.|
|Native Mean||The original mean of all values from the original dataset prior to geoprocessing in GLOBE.|
|Native Median||The original median of all values from the original dataset prior to geoprocessing in GLOBE.|
|Globe Range||The range of values of the GLOBE transformed dataset after geoprocessing using Globe Land Units.|
|Globe Mean||The land area-weighted mean of values of the GLOBE transformed dataset after geoprocessing using Globe Land Units.|
|Globe Median||The land area-weighted median of values of the GLOBE transformed dataset after geoprocessing using Globe Land Units.|
|% Native||The percentage of data coverage across GLOBE’s Globe Land Units covered by the original global variable data.|
|% Extrapolated||The percentage of extrapolated data coverage across GLOBE’s Globe Land Units based on original data when it was appropriate and/or possible to extend the variable (e.g. mean temperature can be extrapolated, whereas world protected areas cannot).|
|% Missing/no data||The percentage of land coverage across GLOBE’s Globe Land Units that contains niether native nor extrapolated data.|