The point was that someone filling out a diary may not actually be listening. They are SAYING they listen at those times. It depends on who fills it out. Stations sometimes get credit due to longevity or memory. PPM is probably more accurate, but is has flaws as well.
Any survey technique has "flaws" as it is an effort to take a small sample of a large group and projecting it mathematically into the total universe being studied. That is why all surveys and polls have a margin of error.
In most consumer fields, a small error is not critical. If a station has a 4.2 or 4.4 or a 3.9 it is going to get on the same buys, and all the top measured stations can do well. That's different from an election poll, where there is only one winner and everyone else gets nothing. And this is why polls get a "bad name" in that close elections often show the polls to be "wrong".
No, people generally do not put additional listening in a diary. They do "round" and say "9 AM to 10AM" while the people meter may show "9:12 to 9:47". In the diary, that is 4 quarter hours. In the PPM, it is 2. But in all my visits to Beltsville, Laurel and Columbia, including many of the "Consultant Fly-In" sessions and reviews of millions of diaries, I never heard any comments about people saying they listened more than actual listening.
Yes, there are inaccuracies. I have seen many. Arbitron established a whole series of validation procedures, including call-backs for clarification.
An example I have cited before was something I saw when reviewing diaries for WIND in Chicago, which had been a Spanish language station for nearly a decade at the time. The diary entry was for the morning show talent on WGN but with the call letters of WIND. Several people made the same mistake... all those entries were over 70, and they had been "branded" with a former station of a present talent. Arbitron split the entry between WGN and WIND in a process called ascription. Not perfect, but it minimizes errors and causes them to have little impact on the overall results.
By the way, I was not a constant adoring fan of the diary. I was on a list on the wall of the head of diary review in Columbia of programmers and consultants who had gotten books reissued from finding ascription errors; I got four books reissued and up until recently, was the only one who ever got a trend report reissued.
Arbitron used to offer McDonald's coupons hoping it would entice people to fill out diaries. If Buddy is asking random people about Radio, maybe it has some value to him. You are correct about the general loss of passion for Radio...
I've been involved with Arbitron and Nielsen for decades. I did my first diary review in Beltsville in 1970 and did my last one in Columbia just before Nielsen moved the processing to Florida.
I never saw coupons sent with recruit packets. They would send different amounts of money depending on the difficulty in recruiting different demos.
In the PPM, you can earn a variety of things based on a residential group (family or other) being compliant, staying on the panel, finishing the first month, etc.
Of course, I ran a research division of a major broadcaster for a decade, so perhaps I have greater inside knowledge of how ratings are actually done...