This ranking is done by a German non-profit organisation, and is basically an average from the results of the strictest international extra virgin olive oil competitions.

This means that only the competitions that meet the following requirements (taken from the link I posted):

Requirements that have to be met by the competitions in order to be considered for our ranking are as follows: ✓ producers have to sign at least a self-certification of sample authenticity including: name of producing mill, tank/batch number, tank/batch size; the competition reserves the right to cross check the winning olive oils ✓ olive oils presented to a competition need to be from a homogeneous lot of at least 500/2000L (separation of small (<5000L) and larger producers >5000L, total production); small and larger producers need to be evaluated separately by the competition when differentiating between lot sizes ✓ producers need to present a chemical analysis not older than 6 months carried out by a COI/IOC accredited or another official laboratory ✓ producers shall present of a sensorial analysis not older than 6 months carried out by a COI/IOC accredited laboratory/panel (optional) ✓ competition needs to execute an upfront secret coding of the samples received from the producers, preferably samples to be handed into the competition in anonymous bottles ✓ the competitions panel needs to be composed exclusively of internationally recognized and trained olive oil experts (minimum 5 judges per table/group, preferably 8) ✓ application of COI/IOC standards in evaluation of EVOOs (like codified samples, official tasting glasses etc.) ✓ use of COI/IOC(-like) profile sheet in the assessment of EVOOs ✓ competition must not have any intention to generate profits through participation fees ✓ competition organizers understand that WBOO will accept and compute per category ONLY a first, second, third prize winner plus max. 7 finalists in order, NOT large numbers of Gold, Silver, Bronze Medals (or similar) In addition to that, WBOO awards another 10 + 10 points for complying with the two most important requisites based on / derived from the rules of the “Mario Solinas Quality Award”, which are as follows: ✓ collection of samples and documentation of the process by a notary/equivalent legal representative (+ 10 points) or ✓ notarial lot confirmation and notary guided competition process after sample reception (+ 10 points) ✓ acceptance of ONLY ONE sample per producer/group of companies per category (i.e. ripe / light green / medium green / intense green or conventional / organic or national / foreign or monovarietal / blend) (+ 10 points) In total a maximum of 40 points can be achieved per EVOO in a single competition. The detailed table how each international olive oil competition is being considered in the WBOO ranking can be found in Annex 1 of this document. The ranking of World’s Best Olive Oil mills is being determined by considering the mills which have produced the olive oil lots corresponding to the brands that have been entered into the competitions, in case the brand owner is different from the producing olive oil mill. Brand owners generally have to declare production sites. Points are being computed under the name of the registering company / entity and are not being consolidated under names of groups of companies in order to avoid registration of samples by large groups of companies under multiple entity names.