I did reporting at KQED and the only reason I gathered was that it’s easier – when you’re standing or sitting (often no table), holding a mic or otherwise dealing with recording, you’ve got a bag on your shoulder, you’re often in a crowd, ..... – basically you’re managing a lot and it’s physically easier to hold and jot down notes on a firm, narrow tablet. Imagine trying to hold and write on a big clipboard or normal-sized pad. Also, it’s socially less awkward, and possibly less intimidating in interviews – you can easier maintain a casual/intimate tone.

I just checked Wikipedia: http://en.wikipedia.org/wiki/Reporter’s_notebook, which confirmed what I thought, and added that it can fit in the breast pocket (obviously male-specific so I didn’t think of it!).

I was also taught to use the top 2/3 of each page to note the facts, and the bottom 1/3 to note my impressions.

I think they are probably easier to hold onto while your writing something.

I feel because it fits into the palm of their hand allowing their fingers to grip it as they write.