sytyguy
Moderated User
http://home.comcast.net/~paxrtp/rtp2012.html
The PAX index, calculated each year by the “Professional Autocross” people (whoever they are) is a commonly used handicapping system for comparing times of cars which are not in the same class. The index is composed of data from across the country, and tries to take the driver out of the equation and compare only the cars. These indices are based on cars prepared to the limit of the rules and driven by top drivers. The index is multiplied against your run time to provide the time you would have had if you had been in an A-Modified car. It is interesting to compare the index of one class to another to see how much time you should gain if you prepared your car to, for instance, Street Prepared rules. Look in the rule-book to find out where your car would be if you made modifications. You can also see that alphabetically, higher cars are not necessarily faster.
PAX could best be described as a relative index of performance in autocrossing, much the same way a handicap rating is given in the game of golf. PAX indexes are based on results from the SCCA National Championships (the best of the best) each September and other regional data throughout the year (Dixie Tour, etc...). How strongly a class performs compared to the thirty-something other classes represented helps determine PAX indexes the next year. The following is an example showing how PAX is used at events...
The class "A Modified" is the fastest class in autocrossing; it is expected that the cars in this class represent the pinnacle of autocross-specific race car design, engineering, and performance. The class rarely disappoints! Due to its unbelievable performance the PAX index for this class is 1.000 (no handicap is given). This means that if an A Mod car runs a time of 50 seconds, it will show up on the final results as 50 seconds. Now let's compare this to a car in "C Street Prepared", which has a PAX index of .857. A car in CSP runs a time of 62 seconds on the same course as the A Mod car, yet its time will appear as 53.134 on the final standings. This was done by multiplying the raw time by the PAX index. As a result, the CSP car finishes only 3.134 seconds (not 12 seconds) behind the A Mod car. Yes, it still lost based on raw speed alone, but it allowed the driver in the CSP car to finish much higher overall. Thus, most regions base their overall driver championship on PAX performance whereas class championships are based on raw times.
The PAX index, calculated each year by the “Professional Autocross” people (whoever they are) is a commonly used handicapping system for comparing times of cars which are not in the same class. The index is composed of data from across the country, and tries to take the driver out of the equation and compare only the cars. These indices are based on cars prepared to the limit of the rules and driven by top drivers. The index is multiplied against your run time to provide the time you would have had if you had been in an A-Modified car. It is interesting to compare the index of one class to another to see how much time you should gain if you prepared your car to, for instance, Street Prepared rules. Look in the rule-book to find out where your car would be if you made modifications. You can also see that alphabetically, higher cars are not necessarily faster.
PAX could best be described as a relative index of performance in autocrossing, much the same way a handicap rating is given in the game of golf. PAX indexes are based on results from the SCCA National Championships (the best of the best) each September and other regional data throughout the year (Dixie Tour, etc...). How strongly a class performs compared to the thirty-something other classes represented helps determine PAX indexes the next year. The following is an example showing how PAX is used at events...
The class "A Modified" is the fastest class in autocrossing; it is expected that the cars in this class represent the pinnacle of autocross-specific race car design, engineering, and performance. The class rarely disappoints! Due to its unbelievable performance the PAX index for this class is 1.000 (no handicap is given). This means that if an A Mod car runs a time of 50 seconds, it will show up on the final results as 50 seconds. Now let's compare this to a car in "C Street Prepared", which has a PAX index of .857. A car in CSP runs a time of 62 seconds on the same course as the A Mod car, yet its time will appear as 53.134 on the final standings. This was done by multiplying the raw time by the PAX index. As a result, the CSP car finishes only 3.134 seconds (not 12 seconds) behind the A Mod car. Yes, it still lost based on raw speed alone, but it allowed the driver in the CSP car to finish much higher overall. Thus, most regions base their overall driver championship on PAX performance whereas class championships are based on raw times.
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