Opportunity to see the ad at least once, based on Frequency and Shared Space
Based on OTS algoritm below.
Ex 50% Shared space and 3 visits (frequency)= 88% OTS

Panelist frequency
Number of visits to the site per day. The information is given by the panelist at each survey occasion.

Panelist exposures
How many times has the ad been shown in average to each panelist.
Ex 25% Shared space and average frequency 5 = 1.25 times.