[2] Gross rating points are a measure of the impact by a campaign using a specific medium or schedule.
[6] Since "the required frequency changes with the product and the competitive climate it is in",[2] the purpose of the GRP metric is to measure impressions compared to the number of people in the target for an advertising campaign.
For conventional media such as radio and TV, multi-tasking has reduced the value per GRP, and a measure named Persuasion Rating Point (PRP) was proposed in mid 2020.
[7] "One GRP is one percent of all potential adult television viewers (or in radio, listeners) in a market."
[2] GRPs are simply total impressions related to the size of the target population: They are most directly calculated by summing the ratings of individual ads in a campaign.