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Hotshoefactor:

Adjustment Factors - Thesite offers a graphical history of PAX factors and and additional setof adjustment factors that are calculated from the fastest run times ineach class at national events. We call this factor StatisticallyNormalized Autocross Performance (SNAP). SNAP factors reflect actualperformance in class, not the performance potential. For well attendedclasses with fully developed cars this works very well, but for otherclasses the differences between PAX and SNAP can be significant. SNAP is not intended to replace PAX. It is just another way to look at class performance. For example, a SNAP of 1.15 means that this class ran 15% faster than the median run time for all classes during the previous season.

I'm a little confused by the PAX vs SNAP. At first, I thought it would be a theoretical adjustment against PAX, but some classes have a SNAP over 1 but an unpredictable +/- on the PAX vs SNAP.

125

1.151

0.957

3.08 %

AM

1.147

1.000

-1.63 %

 

Is it just a difference between the two adjustments?

I apologize for the late reply. SNAP and PAX work differently as far as the reference point is concerned. For PAX the A Modified class is the reference point, i.e. all adjustment factors are relative to this class. Only a class that runs faster than AM could have a PAX greater than 1.You all know this.

For SNAP the reference point is the median run-time for the fastest drivers from all classes. To get the SNAP factors we calculate the median run times for each class and divide it by the median run time for all classes. The result is a factor that tells us how much slower or faster than the median a given class has run historically.

 To use your example, the SNAP factor of 1.147 for AM tells us that AM typically runs 14.7% faster than the median of all classes. To put it's times on the same footing as other classes we bump up AM run times by 14.7% by multiplying with 1.147.  The SNAP factors for classes that are normally running slower than the median, the adjustment factors are less than 1 so the times are reduced when we factor them.

 To compare PAX and SNAP we first have to correct for the different normalizations. We do this by setting the median SNAP equal to the median PAX. The percentages are calculated off of these homogenized PAX and SNAP factors. This seems to be the most robust way of comparing the two sets of adjustments, but it does make it hard to check the calculation by simply inspecting the respective numbers.

For those of you who like their stats, here is a table that shows how much faster or slower than the median a given class ran at national events (Tours & Championship). Positive percentages mean the class ran faster than the mean, negative percentages mean it ran slower. The calculation is based on roughly the fastest 30% of runs in each class wiith a minimum number of competitors.More detail and the corresponding PAX & SNAP factors can be found here.

Happy New Year! Making use of the off season, we added several new features to HotshoeFactor.com for 2010.

• Driver Profiles provide a summary of your ranks and finishing positions over the years. Event details showing class and finishing position are also available. This is the most efficient way to get an overview of your autocross accomplishments!
• Embed HotshoeFactor.com results in your website! Regions can now embed their latest HotshoeFactor.com results and ranks in their websites with just one line of HTML code. You can also embed your recent finishes and your ranks into your website. The widgets automatically update as new information becomes available. Follow the link to see examples. The embedding code for specific organizations and drivers is available on the corresponding pages on HotshoeFactor.com.
  

Please let me know if you want to add your 2010 results to our database. All we need is someone to alert us when new results are posted and access to some form of computer readable results file (csv, html, AxWare files, etc).

Thank you!

Martin