CF = [(SSA-30)/ Actual Course Length] * 20,000
This gives a ratio of SSA to Length.
The 20000 is a weighting factor that gives a more useful number on a 1-100 scale.
(Use Actual Length instead of Effective Length. If you use Effective Length then that number also takes into account all of the factors that influence SSA [foliage, elevation, forced layups, OB trouble] and the effect on SSA and the effect on length cancel each other out. If you use Effective Length the CF comes out to always be the same number.)
CF needs to be grouped by Course Level
Courses need to be grouped by difficulty from Gold to Green, with Gold as the most difficult and Green as the least difficult.
You have to start by understanding the concept of Course Levels. The course level corresponds to the player level that a course is designed for. The levels from highest skill level to lowest are Gold, Blue, White, Red, Green. These courses are designed and most suitable for players in specific Player Rating (PR) ranges. E.g.- Gold 975-1025, Blue 925-974… For simplicity you can think of it as Gold 1000, Blue 950, White 900, Red 850, Green 800.
The best way to conceptualize these course levels is to use an analogy from Traditional Golf (TG). While many aspects of TG don’t carry over to DG, some do, and this only an analogy to aid understanding. On a TG course with Blue, White, and Red tees all would agree that Blue is the most difficult, White is in the middle, and Red is the easiest. The problem with disc golf is that most courses only have one set of tees, and it’s not usually apparent what Level the course is. A few courses are Gold, some are Blue, lots are White, some (mostly older) are Red, and a few are Green.
To help conceptualize the course levels imagine Renaissance with 5 sets of tees -- Gold, Blue, White, Red, Green. The Gold course is the longest and most difficult and the Green course is the shortest and easiest. The SSA is highest for the Gold tees and lowest for the Green tees. Now take a 1000 rated Gold level player, like Stan McDaniel. Everyone would agree that, as reflected by his scores, Stan would find the Gold tees to be the most difficult and the Green tees to be the easiest.
Now we’re finally getting back to how the CF relates to course levels. Since all of these 5 layouts at Renny are on the same land they will have basically the same amount of foliage, OB, greens, and elevation changes; therefore the Challenge Factor (CF) should be basically the same for each layout. Based on the CF alone, the Green layout would appear to be just as difficult as the Gold layout, but we’ve just shown that’s not the case, so it makes more sense to order each level by difficulty from Gold down to Green.
Please see the attachments below for confirmation of these assertions. Especially notice how the courses came out when they are NOT grouped by Course Level. For example, notice the 3 layouts of Buckhorn in New Hill NC. Clearly, for a 1000 rated player, at Buckhorn the order of difficulty goes from Blue tees to White to Red, with the Blue layout significantly harder than the Red layout.