Full details of how to understand what
the ratings mean and how to calculate a rating are listed below.
Explanation of the table:
A rating
for each team is obtained by dividing their total points by their
match/series total, with the answer given to the nearest whole
number.
The
match/series total for each team combines the number of Tests played
and the number of series played (minimum series length two Tests).
It includes all series completed since August 2002 but for series
completed prior to August 2004, this number is halved, so these
earlier matches have a lower 'weighting'.
The number
of points earned by a team for any given Test or series depends on
two factors: the result (won,
drawn/tied or lost) and the rating of the
opponent against whom the result was achieved. The higher
an opponent's rating, the more points are earned for beating them.
Points are ‘weighted’ in the same way as the match/series total.
A team
that over the period being rated wins as often as it loses while
playing an average mix of strong and weak opponents will have a
rating of close to 100.
Calculating the ratings:
There are
two steps to calculating the rating of sides at the conclusion of a
series. Firstly the series result
must be determined and then the rating
points formula can be applied.
(a) Determining the series result:
At the
end of each series, the series result
is determined by awarding one point for each Test win and
half a point for each Test draw. In addition, for any series
consisting of two or more matches, there is a bonus point
available for the series winner or half a point to both teams if
the series is tied. For example:
A five
match rubber finishes 2-1 with 2 draws. The
series result for rating
purposes is 4-2. (The winning team has two wins worth one point,
plus two half point draws, plus an extra point for the series
win.)
The
two figures in the series result (4-2 in the above example) are
referred to as series
points scored
and series points conceded
respectively.
For
series of at least two Tests, the total series points available
will therefore be one more than the number of Tests played in a
rubber. This total is the number by which the matches column
will increase in the rankings table.
(b) Applying the rating points formula:
The
series result derived above is
then converted into a certain number of rating points for each
team. These points are then added to their existing total and used
to generate their updated ratings.
The
number of rating points a team scores for a given series result
will depend on the gap between the ratings of the two teams going
into the series.
There
are two different formulas. One applies if the gap between the two
teams' ratings is less than 40 points, the other if the gap is 40
points or more.
Case 1 - if the gap between the two teams' ratings at the start
of the series is less than 40 points:
The number of rating points scored by each team equals:
(series points scored) multiplied by (50 points more than your
opponent's rating) plus
(series points conceded) multiplied by (50 points less than your
opponent's rating)
Case 2 - if the gap between the two teams' ratings at the start
of the series is 40 points or more:
The number of rating points scored by the stronger team equals:
(series points scored) multiplied by (10 points more than your own
rating) plus
(series points conceded) multiplied by (90 points less than your
own rating)
The number of rating points scored by the weaker team equals:
(series points scored) multiplied by (90 points more than your own
rating) plus
(series points conceded) multiplied by (10 points less than your
own rating)
These figures are then added to the existing points. This is
divided by the new match/series total to produce the new rating.
Practical example:
The
following example illustrates how the formula was applied in
practice to an actual series.
India v West Indies, November 2002
India (rated 92 at the time) played West Indies (rated 80) in a
three Test series. India won two Tests with the other drawn.
The series result for rating
purposes was India 3.5 West Indies 0.5. (India earned one point for
each of the Test wins plus a point for winning the series. Both
sides earned half a point for the drawn Test).
The gap between the teams' ratings was less than 40 so the formula
in Case 1 applies
The rating points scored by India were: 3.5 (their series points
scored) multiplied by 130 (50 more than West Indies' rating) plus 0.5 (their series points conceded) multiplied by 30 (50
less than West Indies' rating) which equals 470
Similarly, West Indies scored: 0.5 (their series points scored)
multiplied by 142 (50 more than India's rating) plus
3.5 (their series points conceded) multiplied by 42 (50 less than
India's rating) which equals 218
Before the series, the table would have shown India with 3297 points
from a match/series total of 36 and a rating of 92 and West Indies
with 2549 points from a match/series total of 32 and a rating of 80.
The next step is to add India's 470 points and West Indies 218
points from this series to the table.
India then have 3767 points from a match/series total of 40,
increasing their rating to 94 while West Indies have 2767 points
from a match/series total of 36, with their rating falling to 77.
Note that the match/series total has increased by 4 (India 36 to 40,
West Indies 32 to 36). This equals the series points available,
corresponding to the three Tests played plus the bonus point for the
series result.
