Why is the NP score in my tailored repository different than the NP score in the Global assessment for the same region?

[ningningj]

Question from OHI - New Caledonia (CNC):

In the global OHI assessment, the NP score for CNC is 100. However, in the CNC repository, the score dropped to 46. We haven't changed the functions or data layers. I'm wondering why the scores are so drastically different. Thanks.

[ningningj]

When creating an OHI+ repository, we copy the same functions and pull out data layers from OHI-Global that correspond to the same regions. In most cases, the global scores and local scores do not differ much. However, scores could change noticeably between OHI-Global and OHI+ repository when a region's data was gapfilled in the global OHI assessment.

When there is no data for a data layer in a specific region, our core OHI engine (ohicore) is able to gapfill for this region based on a suite of criteria and formation (eg. neighboring regions data, etc). In CNC's case, two NP data layers ("cyanide" and "blasting") were gapfilled in the global study for this region.

This process occurs in the status calculation process (in functions.R) without changing the raw data layer itself. Therefore, when CNC repository was created and data layers were pulled for this region, "cyanide" and "blasting" were left blank again as there was no regional data. A random value was used as a placeholder until local data replaces it, which would change NP score from what you see in OHI-Global.

To check which layers have these placeholder values
When you receive your repository, you can check in the layers folder. All "placeholder" values are labeled in the file name: