On your pace at Sawtooth 100: what 2012's 50-mile splits tell us about slowdown

In 2012, runners who finished Sawtooth 100 slowed down by an average 39.75 percent from their first half (start to Finland, 51.2 miles) in their second half (Finland to finish, 52.1 miles). The proof:

• 2012 Sawtooth 100 results, with 50 mile splits (all but two runners have 50-mile splits) (PDF)
• 2012 Sawtooth 100 slowdown, analyzed

Here's what the data tells us:

• 89 finishers, 87 who have 50-mile splits
• Average slow down for all finishers was 39.75 percent; median was 37.9 percent
• The most even splits were from the top woman, who slowed down 7 percent
• The most lopsided splits were from the 45th finisher, who had almost a 1:2 time ratio between the first and second halves
• 25 people finished under 30 hours, with an average slow down of 35.88 percent; 32 people finished under 32 hours with an average slow down of 36.76 percent.
• The standard deviation for all runners was 14.33 percent, meaning two-thirds of all runners slowed down +/- 14.33 percent from the average of 39.75 (a range of 25.42 to 54.08 percent slowdown)
• The standard deviation for runners who went sub-30 was 14.99 percent, slightly wider than the group of all runners.

Being that I set my original pace chart at about a 22 percent slowdown (based on finishing 55 percent of the distance of half of my goal time and the remaining 45 percent of the distance in the remaining time), my goal is on the lower end of one standard deviation away from the average from last year's results. That's enough to make me think about it again.

Statistically, if someone runs a 30-hour finish on this data, two-thirds of the time they will be at Finland between 12:00:00 (50 percent slowdown) and ~13:36:00 (20 percent slowdown) elapsed. 

Tab two of my 2013 Sawtooth Pace Chart has my goal finishing times adjusted to account for at 35 percent slow down. Basically it takes my pace to Finland down 14:54/mi and my pace to the finish up to 19:52/mile. A similar exchange is made for my 32 hour pace.

I'd be very curious to see similar data from prior years.