Difference between revisions of "Correlated Instant Borda Runoff"
imported>DanBishop 
Psephomancy (talk  contribs) (Rename category) 

(3 intermediate revisions by 2 users not shown)  
Line 1:  Line 1:  
−  Correlated Instant Borda Runoff (CIBR) is a [[preferential votingpreferential]] [[voting system]] for singlewinner elections, devised by Ken Kuhlman in May 2005 in order to reduce Borda's susceptability to [[clones]]. 
+  Correlated Instant Borda Runoff (CIBR) is a [[preferential votingpreferential]] [[voting system]] for singlewinner elections, devised by Ken Kuhlman in May 2005 in order to reduce [[Borda]]'s susceptability to [[clones]]. 
== Procedure == 
== Procedure == 

Candidates are scored according to the [[Borda count]]. The Borda loser of the [[candidate correlationmostcorrelated]] pair of candidates is eliminated. The process is repeated until only one candidate remains. 
Candidates are scored according to the [[Borda count]]. The Borda loser of the [[candidate correlationmostcorrelated]] pair of candidates is eliminated. The process is repeated until only one candidate remains. 

+  
+  == Example == 

+  
+  {{Tenn_voting_example}} 

+  
+  The [[Borda]] scores for the four candidates are: 

+  
+  * Nashville: 194 

+  * Chattanooga: 173 

+  * Memphis: 126 

+  * Knoxville: 107 

+  
+  If "correlation" is defined as [[thirdorder correlation]], then the mostcorrelated pair is Chattanooga and Knoxville. Knoxville has fewer Borda points and so is eliminated. After this elimination, the Borda scores for the remaining candidates are: 

+  
+  * Nashville: 126 

+  * Chattanooga: 90 

+  * Memphis: 84 

+  
+  and the correlations are: 

+  
+  * Nashville & Chattanooga: 100% 

+  * Nashville & Memphis: 74% 

+  * Chattanoogs & Memphis: 26% 

+  
+  The new mostcorrelated pair is Nashville and Chattanooga. Chattanooga is the Borda loser of this pair and is eliminated. The Borda scores of the remaining pair of candidates are: 

+  
+  * Nashville: 58 

+  * Memphis: 42 

+  
+  Memphis is eliminated, and Nashville wins. 

+  
+  == Criteria Compliance == 

+  
+  CIBR passes: 

+  
+  * [[summability criterionthirdorder summability]] 

+  
+  It fails: 

+  
+  * [[Condorcet criterion]] 

+  
+  
+  [[Category:Singlewinner voting methods]][[Category:Ranked voting methods]] 
Latest revision as of 19:03, 12 April 2020
Correlated Instant Borda Runoff (CIBR) is a preferential voting system for singlewinner elections, devised by Ken Kuhlman in May 2005 in order to reduce Borda's susceptability to clones.
Procedure[edit  edit source]
Candidates are scored according to the Borda count. The Borda loser of the mostcorrelated pair of candidates is eliminated. The process is repeated until only one candidate remains.
Example[edit  edit source]
Imagine that Tennessee is having an election on the location of its capital. The population of Tennessee is concentrated around its four major cities, which are spread throughout the state. For this example, suppose that the entire electorate lives in these four cities, and that everyone wants to live as near the capital as possible.
The candidates for the capital are:
 Memphis, the state's largest city, with 42% of the voters, but located far from the other cities
 Nashville, with 26% of the voters, near the center of Tennessee
 Knoxville, with 17% of the voters
 Chattanooga, with 15% of the voters
The preferences of the voters would be divided like this:
42% of voters (close to Memphis) 
26% of voters (close to Nashville) 
15% of voters (close to Chattanooga) 
17% of voters (close to Knoxville) 





The Borda scores for the four candidates are:
 Nashville: 194
 Chattanooga: 173
 Memphis: 126
 Knoxville: 107
If "correlation" is defined as thirdorder correlation, then the mostcorrelated pair is Chattanooga and Knoxville. Knoxville has fewer Borda points and so is eliminated. After this elimination, the Borda scores for the remaining candidates are:
 Nashville: 126
 Chattanooga: 90
 Memphis: 84
and the correlations are:
 Nashville & Chattanooga: 100%
 Nashville & Memphis: 74%
 Chattanoogs & Memphis: 26%
The new mostcorrelated pair is Nashville and Chattanooga. Chattanooga is the Borda loser of this pair and is eliminated. The Borda scores of the remaining pair of candidates are:
 Nashville: 58
 Memphis: 42
Memphis is eliminated, and Nashville wins.
Criteria Compliance[edit  edit source]
CIBR passes:
It fails: