In Come Dine With Me, it is widely recognised that the first contestant has the most difficult dinner to host. The competitors not only meet for the first time but they also don't know what the standard is. Once the first meal is out of the way the subsequent ones can be compared to it: in other words we need a comparison before we can make a decision.

As we all know the first televised party leaders' debate transformed this election. Nick Clegg claimed the plaudits for an all round performance which projected him and his party into the public's consciousness in a way that has never happened before. The Lib Dem leader's bravura display has immediately led to increased poll ratings and he is fervently hoping that this in turn will translate into votes.

However Clegg's surge in popularity may not be due just to the debate, it may be that we are better able to make a comparison: otherwise known as relativities or the Come Dine With Me effect. Before the election the choice was clear: Labour v Conservatives, Brown v Cameron, Status Quo v Change. As long as there were only two options, David Cameron could naturally assume the Change mantle. Clegg's rise however now means that we have a Change candidate comparison and it is this that helps to explain, partially at least, both the increased standing of the Liberal Democrats and the slide of the Conservatives. Clegg contrasts himself to the two other party leaders making it clear that he is radically different from them. The comparison that is the most telling though is the one between him and the Tory leader.

The application of relativity to decision making is well researched and well established. If this analysis is correct then, it should mean that rather than fighting on two fronts ('A curse on both your houses') which the Lib Dems traditionally have to do , they should, in the latter phases of this campaign seek to focus their attention on the contrast between themselves and the Tories as the real Change party.