From: sommar@enea.se (Erland Sommarskog)
Newsgroups: rec.music.misc,alt.rock-n-roll
Subject: UAP #21 - Billy Joel
Keywords: Usenet Artists Polls
Date: 6 Sep 92 15:29:46 GMT
Followup-To: poster
Organization: Enea Data AB

Been on the top on the wistlist for a long time, but delayed in
lack of discographies, but finally here he is: Billy Joel! My
thanks to Leo Breebaart and Dan Becker for providing me a
discography.

There is a discography with this article, which you can (and should) 
use as a template for your ballot.

Deadline for this poll is September 19th.

If you are new to these polls, please read the instructions following
the template before you vote. If you interested in reading about the
algorithm I use to compute the results, there is a descpription following
the instructions.

These are the Billy Joels albums I have been informed of. If you feel
some item is missing, please add but remember that bootlegs are not
included. I have also added three albums which apparently are with
groups Joel played in (before his solo career?). These are the three
first items.

&BEGIN
Hassles
Hour Of The Wolf
Atilla
Cold Spring Harbour
Piano Man
Streetlife Serenade
Turnstiles
The Stranger
52nd Street
Glass Houses
Songs In The Attic
The Nylon Curtain
An Innocent Man
The Bridge
Kohcept
Strom Front
Greatest Hits Volume I & II
&END

How to vote
-----------

Use the list above as a template for your ballot. Sort the list
so that your favourite comes right after the &BEGIN and your
least favourite just before the &END. Delete albums you are not
familliar with. One album by line. No numbering. Please delete
quote characters like ">" from your ballot.

If you can't tell two or more albums apart you can declare a
tie. You do this by preceding the albums with &TIE. The tie
lasts until the next &END. The number of &END on the ballot
must be equal to the number of &TIE + one for the &BEGIN.

If you feel that there is a big gap between two albums you
can mark this with a filler. A filler has the format &FILLERn
where n is a positive number, default is 1. Notice that a very
big value of n make little sense; the net effect is the same
declaring an &TIE on the albums separated by the &FILLER.

To participate you need to know at least two albums, so you don't
have to be shy. Ballots are weighted, so the more you albums you
know, the more influence do your ballot get.

For further details on the algoritm, see below if you are interested.

*MAIL* your vote ballot to me, sommar@enea.se. I try to acknowledge
all votes, so if you do not receive an ack after a few days, please
mail me again.

If your mailer leave a decent return address *and* your ballot mail
has a non-empty subject line, you will get the results in your mailbox.
If you want the results to another address, please state so, but no
guarantees.

You are welcome to send in a vote for a friend who does not have net
access. Just indicate that the vote is for someone else so I know that 
it's not a duplicate.

Have fun!

The Algorithm
-------------

This an example ballot for an imagninary group: (The numbers in the
right are NOT part of the ballot as you write it, but are used for
the description below.)

&BEGIN
She Comes in the Morning                      0.5
Next Day                                      0.4
&TIE
Looks Like Trouble                            0.25
Futuralized                                   0.25
&END
On the Way Down                               0.1
Cram it!                                      0.0
&FILLER4
Last Really Crappy Album                     -0.500
&END

The algorithm to compile the results of a polls consists of a
number of steps.

Step 1:
For each individual ballot, the intervall from -0.5 to 0.5 is sliced
up at (N + F + 1) equidistant points, where N = number of entries,
and F = number of fillers. In the example ballot N = 6 and F = 4.
The top album gets 0.5 points, next album ((N+F) / (N+F+1)) - 0.5
points, third best gets ((N+F-1) / (N+F+1)) - 0.5 points etc, down 
the last which gets -0.5 points. If two or more albums are tied,
they get the average of the involved points. The net result for
the example ballot is illustrated by the number on the right side.
(Side note: if we forget the fillers, the method corresponds to the 
one you use for pairs competitions in bridge.)

Step 2:
In order to avoid distortion from voters who only know the 2-3
most popular albums, the ballot is weighed so that the points 
from step 1 are multiplied with sqrt(N).

Step 3:
All ballots are added together and for each album we get a number
of points P = ((p1 + p2 ... pM) * 1000 / M) * C + 500, where M = 
the number of ballots the album appears on, and C is a poll constant.
Thus, the result for an album is indepentent on how well-known it is,
However there is a cut-off rule, so albums which only appears on one
or two ballots are excluded from the final result.

The Poll Constant:
This constant is sqrt(B/T) where B where B is the number of ballots 
in the poll and T is the total number of entries on these ballots.
The idea with the poll constant is to remove the effect of the weighing
factor from the range of the points, so we can compare polls with
each other. If an album tops all ballots, it will get 1000 and 0 if
it is ranked last by all voters. Note however that this compensation
is a rough model. If an album tops five ballots of ten, and is not
mentioned on the other five, its result can be bother higher and 
lower than 1000 depending on the weight of these ballots.
-- 
Erland Sommarskog - ENEA Data, Stockholm - sommar@enea.se
"Recreation of source code from design documentation can be costly"
IEEE Std 1042/1987