I think these kind of calculations should be made in the analysis software (Excel, SPSS, etc) and not in the data collection software (e.g. Limesurvey).
That said, it might be possible to find a way to get this. Not 100% sure at the moment though.
Frist step: you can pass on the weight via a custom attribute in the token table.
Then you could calculate at least the value of each vote. The problem that I see is to get the aggregated value of all voters. There is probably a way, but it is too late. I can't think of how to do this. Maybe someone can pick this up tomorrow morning...