Comdex Ranking
The Comdex is Not a Rating 
The Comdex is not a rating itself, but a composite of all the ratings
that a company has received. The Comdex ranks the companies, on
a scale of 1 to 100, in relation to other companies that have been
rated by the services. The Comdex is an effort to reduce the confusion
over ratings, which is caused by each ratings service using a different
scale.
How is the Comdex Calculated? 
To calculate the Comdex, we first determine the percentiles for
each rating service. We start by counting the total number of companies
rated by the service. Next we count the number of companies in each
rating category. From that data, we calculate the percentile for
each rating category. For Example, let us take a sample rating service
and calculate the percentiles. The Super Rating Service assigns
ratings in five categories, A, B, C, D and E. It has rated a total
of 50 companies as shown below. The percentiles would be calculated
as follows:
A 
5 
100 
B 
10 
90 
C 
15 
70 
D 
10 
40 
E 
10 
20 

50 

We repeat this process and construct a table of percentiles for
each of the rating services. Using these tables, we can now calculate
the Comdex for a given company. We take each rating that the company
has received, and look up the percentile in the table for that rating
service. Then we average the percentiles and factor in the number
of ratings received to give the Comdex.
A company needs to be rated
by at least two rating services to receive a Comdex. The Comdex
is based on the ratings issued by the following rating services:
A.M. Best, Standard & Poor's, Moody's Investors Service and Fitch.
