PAX: The Great Leveler
Is PAX really "The Great Leveler"? Perhaps the following
thought experiment will help you decide:
## The Greatest Driver of the Day
Imagine you have a hundred cars show up at a race, all
different makes and models. You are tasked with assigning
each a handicap such that whoever wins today be dubbed "The
Greatest Driver of the Day."
In a perfect scenario, each car would be given a handicap
based on its performance capability. You might measure this
perfomance capability directly (200m time, skid pad G's,
braking distance) or you might compute it based on some
relevant data points (power, mass, tire size, tire rubber
softness). You could even put an unbiased (ha!) driver in
the cars, and time her on course.
Now you've assigned each car a handicap (which may have
taken most of the day) let's get on to the good stuff!
The race goes on, a winner is declared and touted "The
Greatest Driver of the Day".
## The Greatest Driver From Each Performance Group
The next week you decide to do it again. The same 100 cars
show up, which makes your job easier. You already know the
handicaps! But this week, instead of 1 trophy to give out
there are ten! You could give out trophies for overall
places 1 through 10. OR you could break the 100 cars into
groups of 10 each, and offer a trophy to the winner of each.
Let's say you opt for the latter..
The fastest 10 cars (based on handicap) are in group A. The
next fastest 10 cars are in group B. And so on through the
letter J.
A:
CAR HANDICAP
1 1.00
2 0.99
3 0.99
4 0.98
5 0.98
6 0.95
7 0.94
8 0.93
9 0.93
10 0.92
B:
CAR HANDICAP
11 0.91
12 0.90
13 0.88
14 0.88
15 0.87
16 0.87
17 0.86
18 0.86
19 0.85
20 0.84
C:
CAR HANDICAP
21 0.83
...
As luck would have it, within each group of ten NOT ALL THE
HANDICAPS ARE THE SAME. That is, car #1, #11, #21, #31, #41,
#51, #61, #71, #81, and #91 are the most performant cars in
their respective groups. If you are lucky enough to be in
one of these cars, you have a better chance of winning your
group!
So the race goes on, ten winners are declared: "The best
driver of fast cars (group A)", "The best driver of nearly
as fast cars (group B)", "The best driver of somewhat slower
cars (group C)", and so on.
By multiplying raw times by the average handicap in a given
group, they also declare one of those group winners the
"Overall winner". So ten happy winners go home, one of them
doubly happy for being both "group and overall" winner.
## The Greatest Driver From Each Car-Type Group
Week three arrives, and those same 100 cars have arrived at
your venue again, begging to race. Except one of the
non-winners from last week has a request: He wants to be in
a group of *similar type* vehicles. He doesn't understand
all the fancy math you did to compute the handicap for his
vehicle (a 1969 Camaro---rear-wheel-drive) and doesn't
understand why it is in the same group as 1997
Maxima---front-wheel-drive.
So to concede his request, you change up the groups from
last week. An attempt is made to group similar performance
capabilities in the same group, but to also match vehicle
type. *Obviously this will mean that on average, each group
will have a greater performance disparity between its
fastest and slowest car*. But it makes the Camaro driver
happy, because now he's being beaten by a 1972
Barracuda---rear-wheel-drive, which for him generates
friendly competition and comraderie rather than resentment.
:)
## SCCA Classing & PAX System
And this brings us round to discussing the current (as of 2020)
classing & PAX systems used by the SCCA for autocross (Solo
II) events. Cars are *presumably* grouped both by ability
and by type. Grouping them by ability leaves the least
disparity between slow cars and fast cars in a given class.
In my opinion, grouping them by type generates comraderie
and friendly competition, but leaves more disparity between
slow cars and fast cars in a given class.
PAX is basically the maximum handicap of the cars in a given
class. You may have heard PAX called "The Great Leveler".
But given that it is based on a less-than-perfect classing
system, we might want to redub it "The Crude Leveler That
Did the Best It Could."
Given that it's a *crude leveler*, let's point out a few false
statements:
"Each car has the same chance of winning its class today"
"Each car has the same chance of winning PAX today"
"Cars A and B had the same PAX time today, so those two
drivers must be equally skilled"
## How To Win Your Class or Win PAX
As any crook knows, imperfect systems exist to be taken
advantage of. In reality we are not forced to show up on
race day with a randomly chosen automobile from a stack.
Rather, we know ahead of time what the PAX factory
is for a particular car before we show up. So if
there are two cars in your driveway, you will obviously
choose the one that has the best chance of winning based on
the current class & PAX system. If you are smart and/or in
need of a place to shovel some cash, you may seek to add a
car to your collection that has a good chance of winning the
current class & PAX system. As new cars come out each
year, you might need to reconsider what you're driving each
year in order to keep bettering your odds.
If you are not smart, not in need of a place to shovel some
cash, or willing to get by on something less than winning,
any car will do.