Each answer gets points. A recommendation is worth 100. A mention without a recommendation at position n is worth 100 minus 15 for every place below the first, with a floor of 40, so being named at all always beats being absent. An answer that does not name you is worth 0.
The score is the average of those points over the latest run of every prompt and engine pair from the last eight days. With 15 prompts on three engines that is 45 answers; with 40 prompts on five engines it is 200. Deleted prompts drop out, and an older run never counts twice.
Here is the calculation for a small set. Three prompts on three engines give nine answers: four recommendations (400), one fourth place (55), one seventh place (40) and three answers without your brand (0). The total is 495 points over nine answers, a score of 55. The per engine bars use the same rule restricted to one engine, which is how you spot that Claude is the weak spot while ChatGPT is fine.
The full method, including share of voice and sentiment, is on the methodology page.