Every hour, the system receives scraped results from Amazon for every hourly tracked keyword. When we receive a keyword, we calculate its hourly SOV.
Say a brand appeared in 2 results out of 10, its SOV for that hour would be 20%. As we receive more results, we keep aggregating them over the day. If the brand receives no impressions in the following hour, its aggregate SOV for that day would be (assuming total of 20 results in the following hour): (0+2)/(20+10) = 6.67%