The Ranking System
by
Edward Watson
Computer Sports Network
CSports.net is an automated ranking system
that attempts to rank worldwide players using a uniform and logical ladder
methodology. CSports.net currently covers
1,250 modifications on 50 first person shooter titles. We normally process
around 1.5 million unique player names a day and 16 million unique player names
a month. This equates to about 60 million player hours a month.
Given this magnitude of data and the type of information that it is possible
to get from a public server, our methodology has to be simple, logically/conceptually
believable and applicable to 99% of the modifications out there. The methodology
is based on that used in a traditional sports ladder. If you beat someone above
you, you go up. In practice the way that we do this is as follows:
Every 3 minutes we look at each server and calculate the number of points
each player scored during the 3 minute period. For each player we work out
how many players who rank above them on the ladder they have beaten and we
raise their rank by that number. In addition at the end of each day we apply
what we call “rank gravity” to all players that have not played for a while.
Those who have not played for more than 7 days accelerate on each additional
inactive day towards the bottom of the table.
The result is a dynamic ladder which is always trying to settle out to the "right" rankings.
However at times it can be a little “off”, especially at the beginning of a
ladder (where players are in order of appearance) and when a player starts
out or changes his name. However rank gravity normally sees to it that new
players/names can rise up the ladder to their natural level reasonable quickly.
All in all the rankings seem to work really well even on a large scale. One
of the main benefits of a ladder system is that with one exception, it does
not need to take into account individual scoring methodologies for each modification.
However if a negative score is better then of course the methodology doesn’t
work. But this is rare.
The way to get to the top of any particular ladder and stay there is to play
often (at least once a week) and consistently beat players above you on the
ladder. Of course there are other ways of getting to the top of a ladder that
broadly speaking fall into the categories of cheating or gaming of the system.
If this is your biscuit there is isn’t much we can do to stop you, although
it rather defeats the object of the ladders (additional fun, interest and motivation
for everyone) and eventually you get caught out.
One comment that always amuses me whenever I see it, is that “The CSports.net ranking
is not accurate”. Reasons given vary from “I am ranked far too low, how can
that be right” to “but you haven’t taken into account my role within the game”.
Invariably this comment completely misses the point which is:
1. By definition a ladder based ranking system cannot be accurate for the
following reasons:
a. Any ladder system takes an unequal number of sample points for each
player so it tends to favor those who play more.
b. At any one time there are new players joining a ladder who are always
going to enter at a position that does not reflect their ability. A ladder
is a dynamic entity that is always trying to reach the “right” answer but
is never able to, because of new players and the ups and downs of each
individual’s form over time. What should be important to each player is
the progression of their rank over time, rather than their absolute rank,
hence our emphasis on rank graphs.
2. “Accuracy” is in the eye of the beholder. Conceptually the only way to
rank players by ability is for someone or something to observe each match
that takes place in the world and rank the players according to a whole host
of criteria (eg role, weapon handling skill, movement, use of strategies
and tactics, score, accuracy, tiredness, benefit or not from luck etc). But
most of these measures are entirely subjective and their combination is absolutely
subjective. Any such ranking system, were it possible, would always suffer
from the criticisms of a different point of view on the values of the variables
and their combination.
3. You cannot make subjective judgments using a computer. Even if you could
measure all the necessary variables their mathematical combination would
at worst be a complicated, unintelligible random number generator and at
best reflect the subjective views of its coder.
4. On public servers there is only one available measure on which to judge
players and that is their score over time. Even if all of the above wasn’t
a problem then technically you can’t get the necessary measurements on this
scale without a great deal of coding of a server side app for each game/mod
and then you would need to get the compliance of 100s of thousands of server
operators.
5. The CSports.net ladders are supposed
to be fun. This is quite often forgotten J Incidentally one result of this
philosophy is the implementation of “rank gravity” which can’t be defended
as a valid metric of someone’s ability.
At the end of the day there are only two and half of us at CSports.net and
we try our best to provide a consistent, logical and competent ranking system
that is useful and fun to use. How well founded and useful those ranking systems
are depends very much upon the communities that we serve. If the people within
those games communities feed back the problems (odd mods, missed mods, missed
servers, missed players etc.), then we can adjust what we do to make the system
more useful and as a result more fun for that community.