**FAQ 1. Where do the scaling factors used in the formula come
from?**

The NCAA formula is: [ { (8.4 * yards) + (330 * touchdowns) - (200 * interceptions) + (100 * completions) } / attempts ].

In 1979, when the NCAA developed the passing efficiency formula, they used average statistics from the previous 14 seasons of two-platoon football (which started in 1965). "8.4" was chosen so that the average passer would have a rating for yards-per-attempt and completion percentage of exactly 100. 330 (3.3 times touchdown percentage) and 200 (2.0 times interception percentage) were chosen to cancel each other out for the average passer.

Passing statistics have improved since the '60s and '70s (in part due to more liberal use-of-hands rules for offensive linemen), to the point where a rating of 100.0 is not an "average" passer but rather a fairly poor one.

**FAQ 2. What about the NFL formula? How is it different?**

The NCAA and NFL formulas are fundamentally similar, in that both compute the rating as the sum of points awarded in the same four categories:

- Completions-per-attempt (completion percentage),
- Yards-per-attempt,
- Interceptions-per-attempt, and
- Touchdowns-per-attempt.

The main differences between the formulas are:

- Those quantities are scaled differently. For example, the NFL awards 4.17 points per yard-per-attempt, while the NCAA awards 8.4.
- The more important difference is that the NFL values are "capped," while the NCAA values are not. For example, the NFL caps for completion percentage are 30% (low end) and 77.5% (high end). A passer who completes 90% of his passes gets the same score for completion percentage as one who completes 77.5%. A passer who completes 10% of his passes gets the same score for completion percentage as one who completes 30%.

Due to the "caps" the NFL formula is slightly harder to compute. Also, generally, NFL ratings are lower for the same statistics (a rating of 100 is an exceptional NFL passer, but a below-average NCAA passer).

For more information on the NFL formula, see this article on NFL.COM.

Here is how to set up a "canned" query to this form:

- Cade
McNown (UCLA) 1997 NCAA-leading season statistics
The link is:

`<A HREF="http://stassen.com/football/cgi-bin/calc-pe.pl?a=283&c=173&y=2877&t=22&i=5">`

The form arguments are "a" (attempts), "c" (completions), "y" (yards), "t" (touchdowns), and "i" (interceptions).