Gerrymandering Multi Ridings

[New Democracy]

Dear List members

     I received the following letter in regards to my request for someone
to gerrymander multi districts. I following it with my reply letter to
Julian.

Don
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Don: >>   Enough talk Steve - it is now Show Time - show us Steve how multi
>> member districts can be gerrymandered.
>
Julian: >This is simple.  Take the case of 6 two-member ridings each
>of population P.  (You suggested P=20,000, but I find it
>simpler to explain the general case.)
>
>The quota for election in a two-member riding is one vote
>more than (1/3)*P.  Therefore if (just over) (2/3)*P of the
>voters in a riding support the Bad Party, that riding will
>elect two Bad members and no Good members.  There are a total
>of 3*P Bad voters, so this is enough to put (3/4)*P Bad
>voters into each of four of the ridings, guaranteeing fairly
>comfortable margins of victory for 8 Bad members.  The 4
>remaining members are Good, elected with 100% of the vote in
>their two ridings.
>
>The principal is the same for ridings with more than two
>members, but the disproportionality goes down quickly, to the
>point where with about 6- or 7- member ridings the
>gerrymandering potential is negligible.  This is why 6- or 7-
>members is often cited as a guideline for STV to produce
>approximately proportional results.
>
>However, Steve (?) has already pointed out that the problems
>of smaller parties do not disappear, since if a party has
>enough support in one neighbourhood to elect just one member,
>that support could be concentrated into one riding or split
>into two, depending on the whims of the gerrymanderers.  This
>could be a real threat to more than one smaller party here in
>BC if STV were introduced.  I base this judgment on
>historical patterns of support.  One would hope that smaller
>parties would be given a stake in the Boundaries Commission.
>
>In Ireland the STV ridings are between 3 and 5 members in
>size, and so produce only somewhat proportional results.  My
>guess is that this is also what leads to the party in-
>fighting often cited in Irish politics, and that it would
>largely disappear if the ridings were increased in size.  I
>don't believe it is an intrinsic feature of STV.
>
>Julian
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Don's reply:

Julian wrote:
>
>The quota for election in a two-member riding is one vote
>more than (1/3)*P.  Therefore if (just over) (2/3)*P of the
>voters in a riding support the Bad Party, that riding will
>elect two Bad members and no Good members.  There are a total
>of 3*P Bad voters, so this is enough to put (3/4)*P Bad
>voters into each of four of the ridings, guaranteeing fairly
>comfortable margins of victory for 8 Bad members.  The 4
>remaining members are Good, elected with 100% of the vote in
>their two ridings.
>
>Julian

Don: This is excellent Julian. Not only do you show the evil of only a few
members per riding but you also show one of the evils of using the Droop
Quota.

     The Droop Quota makes it easier for gerrymandering because each riding
is going to automatically have one quota of ballots wasted. This makes it
easy for the persons doing the gerrymandering - they make sure that most of
the wasted ballots are of the other party. If the Hare Quota was used in
this example the results would not be as disporportionate - only seven Bad
Guys to five Good Guys.

For example:
         Ridings:   One     Two    Three    Four    Five    Six
  Bad Guy Voters:   16K     16K     16K     10K      1K      1K
 Good Guy Voters:    4K      4K      4K     10K     19K     19K

 Members elected
        Bad Guys:    2   +   2   +   2   +   1                   =   7

       Good Guys:                            1   +   2   +   2   =   5

I have always been opposed to the Droop Quota but I never knew of its use
in gerrymandering. Thank you Julian - I am going to add this point to my
text as another reason not to use the Droop Quota.

The lessons learned here today is for us to use many members per riding and
for us not to use the Droop Quota. Gerrymandering in this example gave the
Bad Guys one additional member - the Droop Quota gave the Bad Guys a second
additional member.

Regards,

Don


Donald Eric Davison of New Democracy at http://www.mich.com/~donald

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -