Fractional transfer

It has been suggested that this article be merged into Surplus Handling. (Discuss) Proposed since April 2020.

The simplest methods of transferring surpluses under STV involve an element of randomness; partially random systems are used in the Republic of Ireland (except Senate elections) and Malta, among other places. It is a variant of Fractional Surplus Handling.

An alternative is to give each ballot a fractional weighting, to give the effect of subtracting a quota's worth of votes from the winning candidates. Specifically, if the quota is Q, a candidate with V votes is assigned a retention fraction of:

1 - Q/V	if the candidate meets quota
1	if the candidate does not meet quota

The weight of each ballot is multiplied by the retention fraction of it's top-ranked candidate (or, if equal rankings are allowed, the average of the top-ranked candidates).