Selecting the audience for the Question Time Election Leaders Special

Tomorrow night – Thursday 30 April – BBC One will broadcast the last in a series of four party leader events in front of a live studio audience. How are these audiences selected?

The answer is that it depends on the event. For the Question Time Special tomorrow night featuring David Cameron, Ed Miliband and Nick Clegg, the audience will be made up of 25 per cent of people who say they will vote for the Conservative party, 25 per cent Labour, 25 per cent Liberal Democrat, 15 per cent other parties and 10 per cent who are still to make up their minds. This means that each party leader faces the same prospect – an audience where one in four supports him, but where the majority does not. The same approach - i.e. the 25 per cent model – will be used for three Ask the Leader programmes with Nicola Sturgeon, Nigel Farage and Leanne Wood later in the evening.

The thinking behind this is that it will ensure that there’s a level playing field. Each leader engages the audience on the same terms. It also means that the BBC has done all it can to ensure that each leader gets the same shot at a fair hearing with the much bigger audience at home.

Trying to make sure that we select audiences for political discussion programmes in a fair way is really important to the BBC. We put a lot of effort and resources into getting the numbers right. But if you’re a regular viewer of Question Time, you’ll know that once assembled, how audiences express their views can often be pretty unpredictable. That’s part of the excitement of political debate. Sometimes, one group might be louder and more willing to get involved; another - more reticent, less voluble, perhaps not as willing to applaud. Audiences can have a dynamic of their own. It’s politics in the raw – and once we’ve assembled that audience, we’re not going to try and regulate how they react to what the politicians say.

For the regular weekly Question Time, audiences are put together recognising the varying levels of support over time and place for each party and are proportionate: the larger the party, the more people who intend voting for that party are selected for the audience.

The Question Time Special involves a different interaction with the audience. Each leader will be scrutinised - on their own - by a selected group of voters. The party leaders will appear, one after the other, for half an hour each, facing the same group of people. The same principle applies to “Ask Nicola Sturgeon”, “Ask Nigel Farage” and “Ask Leanne Wood”. With only one person taking the questions at a time, we think what’s crucial is that they each receive a consistent level of scrutiny, of support, of opposition.

There is no perfect mathematical way to assemble an audience for these sorts of programmes. Some people think you should do it simply by current opinion polls; others that you should do it according to fixed ratios, such as representation in the House of Commons, or the formula used for Party Election Broadcasts. The fact is, you may well need to take account of all of these factors and more, not least the differences in different parts of the UK.

What’s more, they will often need to be different for different sorts of programmes. With a range of formats, varying panel line-ups and different roles for the audiences – there is no one-size-fits-all way of doing it which everyone agrees about. The formula for the events on April 30, for example, do not relate to current opinion polls. In our judgement, that would not be fair - we would not be giving each of the leaders the same degree of scrutiny.

And, in the end, this is an editorial judgment. It’s for the programme makers to decide how best to put on a TV programme that is fair to the participants and, most importantly, best serves the audience.

• Watch the Question Time Election Leaders Special on Thursday 30 April 2015 at 8.00pm on BBC One