JOURNALISTS interview people, don't they? Well, they do but perhaps not as often as you might think. For the political reporter the press conference, the "doorstep," the "huddle," and chats in bars are the stock in the trade, the main means of extracting information from politicians. At Holyrood there is also a thing called the "Mongolian cluster" (not its full name, but we'll not go into that) which occurs when a group of hacks decides to doorstep some unfortunate MSP at the same time. Which makes it a kind of enforced huddle, I suppose. The "sit down," a formal one-to-one interview, lasting from half an hour to an hour or even longer, is a relative rarity. Partly that's because political reporters are not considered experts when it comes to the human condition. We have feature writers to tease out the inner person, to hold mirrors up to souls, to mine psyches. That sort of thing. We stick to studies by the Institute for Fiscal Studies. Or we try to gauge whether a politician's latest evasive answer amounts to a "humiliating climbdown" when compared with his or her previous evasive answer.

Elections upset this natural order of things. Over the past few days I've sat down with quite a number of people and conducted lengthy on the record phone interview with a few more. It pays to prepare, to consider the the questions carefully but also anticipate the possible answers. It also requires a voice recorder, not just because one's shorthand is hopelessly inadequate but because the conversation should at least feel spontaneous, despite those efforts to structure it.

Transcribing the interviews, I've been struck by several things but one of them is this: Nicola Sturgeon is extraordinarily, almost unnaturally articulate. She speaks in proper, complete sentences. If she introduces a subordinate clause she returns effortlessly to her main point without trailing off or losing the sense. She hardly ever 'ums' or 'ers' or 'you knows'. What is spoken can be typed up without having to be tidied up. Very few people speak like that. For most of us, syntax goes out of the window when we open our mouths.

Being articulate is not the be all and end all. Fluent speakers might express a flawed argument just as easily as they might explain a strong one. Some very bright people can barely string two sentences together. Some brilliant politicians convey their message clearly and passionately while inflicting the most brutal damage upon every bit of grammar in their path.

That's why my proposed new device should not be taken too seriously. But if you are happy to accept those caveats, let me introduce it anyway: the Prescott-Sturgeon Scale.

It calibrates verbal dexterity like the Richter Scale measures seismic activity. Next time you hear a politician interviewed or just chatting (it doesn't count if they are reading a speech from an auto-cue or pouring a pre-mixed soundbite down a television camera lens) see where you would place them. Just for fun. According to my calculations, Ms Sturgeon is nearly off the scale.