6. Eligibility, Selection, and Inclusion Logic
What is included and how it is selected and mapped.
6.1 Product Category Grouping
Everything a provider sells is grouped into product categories at the granularity of a single purchasable item, not a service family. One virtual machine type is its own product category, as is one storage tier. Where a region publishes more than one price for the same product category, the median of those prices represents the region, so that one atypical entry cannot carry the region's position on that category.
6.2 Erroneous Price Removal
For each product category, the price published by every region is compared against the consensus across all regions of that provider. Observed variation in the price of one product category between regions of the same provider stays below a factor of three. A price that differs from the consensus by orders of magnitude holds some other quantity than the one its field claims, and is removed. Where a product category's prices remain mutually inconsistent after that removal, the whole product category is excluded from the pricing score, on the grounds that no consensus exists to compare a region against. The count of prices removed and product categories excluded is recorded for every run, as described in Section 9.
6.3 Comparison Basket Selection
A product category enters the comparison basket only where the provider prices it in at least half of its regions. A product category sold in a handful of places is left out, as too few regions price it for a comparison to hold.
Regions with very small catalogues are excluded from the test of how widely a product category is sold. A newly launched region prices few product categories, and counting it towards that test would raise the number of regions a product category has to appear in at every launch, excluding established product categories from the basket. Those regions are still scored on the basket like every other region.
6.4 Availability Eligibility
The service availability percentage counts a product category only where the provider prices it in more than one region. A product category priced in exactly one region worldwide says nothing about the completeness of any region, as no other region could have stocked it.
A price removed under Section 6.2 still counts towards availability. An erroneous price is still evidence that the provider sells the product category in that region, and availability counts what is sold and not what it costs.
6.5 Carbon Grade Eligibility
A region receives a carbon grade where GPX Grid holds an intensity factor for the grid serving its location. Regions are associated with grids and not with countries, so a country served by more than one grid can hold regions carrying different grades, and two regions in the same grid area carry the same intensity figure whichever provider operates them.
Where no factor exists for the grid a region draws from, no carbon grade is published for that region and the field is left empty. A region launched between runs is graded from the run that follows its launch, so a region newer than the current data version carries no carbon grade until the next one.
6.6 Water Stress Matching
Aqueduct 4.0 reports baseline water stress for hydrological areas finer than a cloud region, together with country-level aggregations. Each region is matched to the Aqueduct area containing its location wherever that area can be identified, and the category published for that area becomes the region's water stress category.
Where a region's location cannot be resolved to a specific Aqueduct area, the country-level figure for the country the region sits in is used instead, and the match is recorded as a country fallback. A country fallback describes water stress averaged across a whole country, and the gap between that average and the catchment a data centre draws from widens in large countries whose water stress varies from one river basin to the next. Which figure was used is recorded for every region, as set out in Section 9.
Where Aqueduct covers neither a finer area nor the country, no water stress category is published and the field is left empty. A region without a water stress category keeps its other three scores, and the absence reflects the coverage of the source rather than an absence of water stress.