@paul
I did one last year. A weeks worth of radio listening recorded. Every day I recorded time & duration, station and device used (FM, DAB, DVB).

Because a DAB radio requires a computer with a digital-to-analogue circuit on its output to decode the signal. Many older DAB sets use generic microcontrollers, which were never designed to run on batteries for any length of time.

How come DAB uses so much power?

FM uses almost no power, in fact if your aerial is long enough you can actually use the power from the radio signal to power your radio and a tiny speaker.

I'm listening to a digital radio feed as I type this - on Freeview. I'd guess the convenience of radio through Freeview makes it quite popular. DAB, on the other hand, is inherently inconvenient - the best place for a DAB radio in any given room may not be where there's a place to plug it in, and if you run them on batteries they tear through them. The reception is unstable and the sound quality is disappointing.

It's my guess that they refer to listening "on Digital" rather than "on DAB" so they can roll the Freeview figures into the equation and thus make DAB seem more popular.

How do they know?
How do they find out who is listening to what radio station and when?
Are these the same people who tell us that 14 million people watched Eastenders?

Personally I think it's just a Gov't ruse to get you to turn to Digital. The Gov't would have us put our flat TV's on the wall and get connected...oh, look at that, they seem to know what we're doing.......