For example, in most elections David Trimble's Ulster Unionist party comes out well ahead of the other parties. But in one particular type of contest, that used for European elections, Mr Trimble's party regularly comes in third place.
Mr Trimble's desire not to finish behind the Rev Ian Paisley's Democratic Unionists and John Hume's SDLP helps explain why he has been lobbying so hard against anything resembling European contests. His party considers it scored a major victory in having an election placed on the agenda, but that sense of triumph would be soured by a contest which relegated it to third place in the pecking order.
Northern Ireland is one of the most regularly polled entities in the world, having experienced 19 full-scale elections in the last 21 years. The statistics amassed over that period show clearly how different types of contest produce different results.
In the House of Commons, for example, the Ulster Unionists hold nine seats while Mr Paisley has three, notching up on average 14 per cent of the vote. His vote goes up, however, in elections to assemblies or to local councils.
This is because in these contests a system of proportional representation is used, with candidates standing in multi-member constituencies. The Ulster Unionist party takes the largest share of the vote in these, with Mr Paisley usually taking around 17 or 18 per cent.
This pattern changes dramatically, however, in European contests. The three Euro-MPs are also elected by proportional representation, but in these cases Northern Ireland is treated as one large constituency. This has the effect of turning the poll into a so-called "beauty contest" in which the leading personalities - Mr Paisley and Mr Hume - attract much larger votes than usual.
This effect is most clearly to be seen in a comparison of the 1993 council elections and the 1994 European election. The DUP performance leapt from 17 to 29 per cent, the SDLP went up from 22 to 29 per cent, while the Ulster Unionists dropped from 29 to 24 per cent. The European result is unlikely to be replicated in any new election, but nonetheless any contest based on a single constituency would be bad news for Mr Trimble.
Many variations of constituency and election type are possible, and the government says no decisions have yet been arrived at on the precise form. It is widely accepted that both council and European elections have democratic validity, but the fact that they produce such different outcomes explains why the present argument on form is seen as so important.Reuse content