Thank you, Michael! I love the internet. It still amazes me that you can find something like that so quickly! I was momentarily thrown off by the irony of the situation and it was only 16 years ago, not 20. Yes, I was referring to the change in the money demos from 25-49 to 25-54. Was a reason given for the change? It can't be that they were looking forward to a time that it would increase baby boomers' viability, can it?
Let me see if I can explain this clearly.
The demos (12-17, 18-34, 18-44, 18-49, 25-34, 25-44, 25-49, 25-54, 35-44, 35-49, 35-54, 35-64 and 55+) had all been there. Through the 60s and into the 70s, 18-49 was generally accepted to be the big money demo in both radio and TV, but there was also advertiser demand in the 60s for teen numbers and 18-34 was hot (among some buyers) for decades.
It's just that 18-49 was considered a "mass audience' and demos on either side of that were considered less so. There were fewer dollars being allocated to reach those audiences. But, especially in saturated markets, filing a niche demo could result in profitable ad sales.
25-49 was a subset of 18-49. It was not a core demo in the way 18-49 was or that 25-54 became. I mentioned it only because it was strategically good for the first AC station that I programmed that wanted something a bit older than 18-49 and a bit younger than 25-54 and I outlined the reasoning for that in my post.
Again (and I may not have said this well before), it really can't be called a "change" and there wasn't "an announcement". It was just a case of ad agencies finding that more clients were willing to increase spending on 25-54, making it a more profitable proposition for stations delivering that demographic. And, over time, once the entire Baby Boom was 25 and older (1989), that demo held within it a massive population bulge.
As to your last question, it's a demographer's job to think about people aging and where significant percentages of population will be in five, ten, twenty or more years, so yes, of course that was part of the equation.
Ad agencies in 1978 had more clients willing to spend more money on stations that did well 25-54 than they did a decade earlier. In 1969, 25-54 was people born between 1914 and 1943. In 1978, it was people born between 1924 and 1953. The big difference? There were no Boomers, the largest generation in history at that time, in the 25-54 demo in 1969. There was seven years' worth in 1979, bringing with them sheer numbers, and a larger percentage of college degrees, which tended to translate to higher earning and spending power.
And that only increased as long as the oldest boomers were 54 or under (the year 2000). But---for B/EZ, it only went so far. The format didn't attract Boomers, so its audience, largely in its 50s and older, aged out rapidly. They made money because, especially in the mid-late 70s, they tended to be #1, #2 or #3 in the demo. And agencies then were more prone to blindly buy the demo, rather than ask if the people they wanted, who happened to be in that demo, were listening to that station. That changed over time.