The Arby books were fudged often. Very hard to make sure the person was not entering their favorite station all day long, even when not listening. In the case of 2 stations sharing the same calls on AM & FM, Arbitron would call to ask and clarify, or use other mechanisms to determine it. Back in the day WLS-FM was promoted as 94.7 and the Top Hour "Z95 WYTZ Chicago @ 94.7" for the sheer fact to separate it from the AM and due to 95.1 in Kenosha being CHR too. B96 was B96.3 and US99.5 was a thing. They needed those Arbitron enters to be exact and correct. That is why with PPM call signs and frequency no longer matter.

Nielsen bought out Arbitron. Companies raise money and stay relevant staying current with technology. PPM is not perfect, it is actually very flawed and like Terrestrial companies did not stay ahead of the game taking IP delivered content seriously.

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