The Arbitron Diary as we know has been replaced with the Nielsen PPM meters.

Arbitron has been around for what seems like forever. I've always wondered how "easy" those little books could be manipulated. There are millions of dollars on the line as advertising agencies examine ratings, demos, etc.

What lead to Nielsen PPM as being the successor to Arbitron? Have there been cases of manipulation where a station gets more listening credit than it should?

Someone might simply write in a given station and nothing else. Also, how precise were those diaries?

As an example, two radio stations who share the same call letters such as WLS-AM and WLS-FM. What if anything happens if a listener simply writes "WLS" in the diary? Which station gets the listening credit?

If someone "forgets" or simply doesn't like the station which is playing, could they not write in another station?

I'm hoping Jeremy Andrews, WYTZZ95FM and John from Wisconsin pass along their thoughts/experiences. These three individuals have shown expertise in the past and I have learned much from them.

Thank you.