Ranking can violate secrecy.

[Mike Ositoff]

> 
> Mike Ositoff wrote:
> > 
> > Interesting. That hadn't occurred to me, about the possibility
> > of a bought voter identifying himself by a unique ranking.
> > It sounds possible, and it sounds like possibly a fatal problem
> > for rank-balloting in many-candidate elections. Is there a
> > solution?
> > 
> > Mike
> 
> Sure.  Limit the number of ranks allowed, with only one vote per
> ranking.  If you want to allow votes for additional candidates, you can

If there are 20 candidates, and people are allowed 4 rank positions,
and we ignore the possibility of shared rank positions, then
a bought voter, paid to rank someone 1st, has about 5800 ways to
fill his remaining 3 rank positions.

As you point out, shared rankings increase that number further.

Mike



> allow the voter to rank them equally in the next-to-last position (as
> well as in the last position, which would be equiv. to truncation).
> 
> Note that allowing multiple equally-ranked candidates in all positions
> would increase the opportunities for a unique pattern.  If you want to
> do this you would need to reduce the max. number of ranks even further
> to compensate.
> 
>