Truncated ballots

[David Marsay]

There are currently two main options for ranking ballots.
1) give first choice (FPP)
2) rank all choices.

I am considering the case where voters are asked to rank, say, their 
top 4 out of 10.

Does anyone know of an references to practical experience with such 
truncated rankings?

The idea is that:

1) FPP discourages voters from expressing their first 
preference when it is unlikely to win. With ranking methods they can 
express their preference and thus help it to build a constituency 
over repeated ballots. It also helps analysts to decide if the result 
is reasonable if the votes record preferences more accurately.

2) Full ranking is tedious. Most methods are pair-wise, and thus a 
candidate who is ranked 9th ahead of the 10th gets equal relative 
benefit  as if it had been ranked first ahead of 2nd. Is this 
reasonable? Will voters take as much care with the lower rankings? 
Might they not be encouraged to vote tactically? ...

For a truncated ranking, one would disregard the lower rankings, 
treating them as if they were equal. It seems to me that this avoids 
the worst faults of other methods, but may introduce some new ones.

(I've been busy on other things for a while, but as Rob is testing 
the system, I thought I'd chip in my half-baked questions now. 
Cheers.)
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Sorry folks, but apparently I have to do this. :-(
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and do not represent the views, policy or understanding of
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