TullyRunners - Article
Some Speed Comparisons of NXN & Foot Locker 2016
by Bill Meylan (December 17, 2016)
Technical Article (for viewers interested in speed ratings) ..... Recent inquiries prompted this article ... Some viewers were interested in the details of "how I calculated the speed ratings" for NXN and Foot Locker 2016 ... and, "Do I think my posted speed ratings are accurate?".
For reference, the speed ratings for the top 35 finishers at NXN and Foot Locker 2016 are posted below (for both boys & girls) ... Complete speed ratings are available on my NXN Results and Foot Locker Results pages ... I evaluated the speed of both races by several different methods typically used when I derive speed ratings ... I also applied criteria learned over years of evaluating Foot Locker and NXN races (consistency of methodology being key) ... and I am reasonably satisfied with the accuracy of my speed ratings.
The 2016 races offer some interesting insights as to the relative quality of the NXN and Foot Locker races ... A discussion of the relative quality highlights some speed ratings considerations, so that's what I'm going talk about in this article.
Graphical evaluation is one method of determining speed ratings ... So for me, any speed comparison includes graphing the results of NXN and Foot Locker on the same graph and interpreting what the graph illustrates ... Below are graphs depicting the actual race times of the top 35 finishers at both races for both girls and boys ... Foot Locker had only 40 runners in each of the girls and boys races, and I excluded the slowest five (not unusual for them to run slower than normal and look like outliers).
Please notice the following on the graphs ... Note how close the race times of the top 35 girls are to each other ... Then see that the boys at Foot Locker ran much faster relative to the boys at NXN.
The top 35 girls at Foot Locker ran an average of 3.6 seconds faster than the top 35 girls at NXN.
The top 35 boys at Foot Locker ran an average of 26.9 seconds faster than the top 35 boys at NXN.
This is a discrepancy ... Why were the boys at Foot Locker so much faster on a relative basis than the girls?? ... The boys and girls at Foot Locker and NXN ran the same course at each (so different course or different distance is not the answer) ... Two reasons typically account for this type of discrepancy when it occurs:
(1) Quality in Terms of Speed
... one group of girls or boys are simply faster than another on a relative
Both of these reasons come into play when evaluating NXN and Foot Locker 2016 ... and evaluating the reasons has an effect on the speed ratings.
Quality Difference Between Foot Locker and NXN 2016
This is about speed ratings, so "quality" refers to speed as measured by speed ratings ... and the "quality" entering each race could be determined by the speed ratings of the top 35 individuals for a relative comparison ... Did the top 35 boys or girls at NXN have higher speed ratings than the same group at Foot Locker entering the race??
There are several "speed ratings"
that might be used to compare the groups:
Projected speed rating is time-consuming ... based on all available speed ratings for each individual plus other relevant information (injury, sickness, travel, racing style, training, etc), you "project" the speed rating for each runner assuming that runner runs a good race ... this is commonly done in horse racing ... I do use it at times for cross country.
The highest speed ratings for the NXN and Foot Locker runners considered in this article are available from my NXN Preview and Foot Locker Preview pages ... So I will use those numbers here to show the "quality" differences between NXN and Foot Locker 2016 ... Here are the average highest speed ratings for the top 35 runners entering each race:
There is no significant statistical difference between the boys at NXN and Foot Locker in terms of speed "quality".
BUT the girls at NXN are 4.7 speed rating points higher than Foot Locker ... or the top 35 girls at NXN are 14 seconds faster (on average) than the top 35 girls at Foot Locker ... and that makes a significant difference ... it definitely comes into play for projected speed ratings.
Effect on the Girls Graph Above ... Since the girls at NXN are faster on average than the girls at Foot Locker, the graph above can not be compared directly for determining speed ratings for each race ... That 14 second faster average for the NXN girls lowers the red squares on the graph above, and that's the reason they come close to the Foot Locker girls ... As noted above, on average, the Foot Locker girls ran 3.6 seconds faster at Foot Locker than the NXN girls at NXN.
Rough approximation ... 14 seconds minus 3.6 seconds = 10.4 seconds ... The speed difference between the girls' races at NXN and Footlocker was roughly 10 seconds (meaning the course at Footlocker ran 10 seconds faster than the course at NXN) based on this single scenario for the girls.
My final total speed determination for the girls (based on several methods at each race) had the Footlocker course running 9 seconds faster for the girls at Footlocker than the girls at NXN.
Four girls ran both Foot Locker and NXN ... They finished in the same order at both races (the boys were not as orderly) ... The table below lists their finishing places, times and speed ratings at both races ... The 9 second variation between races shows quite decently for them.
Course Deterioration for the Boys at NXN Nationals
NXN was run at Glendoveer Golf Course for the third time in 2016 ... the NXN course ran slower in 2016 than the previous two years (easy to prove statistically) ... many runners and coaches talked about the soft and muddy conditions.
The girls ran before the boys at NXN 2016 ... It was evident from the web-cast that several sections of the course were getting "torn-up" somewhat as more and more runners raced those areas ... The course looked deteriorated somewhat for the boys race, but only an evaluation of the final times can determine the extent of the deterioration (if any) ... If should also be noted that the Glendoveer course loops over several areas, so the girls were tearing up parts of the course for themselves (and the front groups of girls were messing up the course for girls behind them).
The speed "discrepancy" between the boys and girls at NXN (as described above & in the graphs) can partially be explained by the "quality" of girls at NXN ... perhaps 14 seconds of the discrepancy is explained by this ... the remainder may be explained by course deterioration ... This is supposition on my part, but I believe these factors are involved.
Seven boys ran both Foot Locker and NXN ... The table below lists their finishing places, times and speed ratings at both races.
Three runners clearly ran better at Foot Locker (Reed Brown, Dylan Jacobs and Gabe Fendel) ... the higher speed ratings suggest most of them ran better at Foot Locker ... Actually, the higher speed ratings mean they ran faster on a relative basis.
I have explained this before ... Foot Locker is unique ... a small field of top elite runners on a course that typically has good conditions and weather that is good as well ... the top runners come to run fast, and they usually do ... There is no other high school cross country race like Foot Locker ... It is very common for the top finishers at Foot Locker to achieve their highest speed ratings.
Relative Basis ... Here is the boys' graph from above with some straight lines drawn that define two groups ... the runners from positions 15-35 parallel each other with a 22 second gap ... the faster group shows a widening gap with the Foot Locker guys getting faster relative to the NXN guys (same quality and some of the same guys) ... the gap at the left-Y-axis is 36 seconds ... this visually illustrates Foot Locker having a relative speed advantage over NXN (this is normal ... in my opinion, it is due to the nature of the race and where it is held compared to NXN).
Casey Clinger did have some separation from the other NXN guys ...Casey Clinger opened a commanding lead in the last part of the NXN race ... I thought he would win by more than 6.7 seconds ... I was told he had a 13-second lead over runner-up Sam Worley at one point, but some runners closed the gap approaching the finish ... His speed rating would have been around 202 had he maintained the gap he opened (but that's speculation).
Using the groups that parallel each from the graph above, it can be approximated that the NXN course for the boys ran 22 seconds slower than the Foot Locker course for the boys (direct comparison due to equal quality) ... But NXN had an additional 160 boys in the their race requiring evaluation ... After applying my other speed determining methods, I came up with a speed variation of 19 to 20 seconds ... People who back-calculate my speed ratings have discovered I almost always use a race adjustment that is a multiple of 3 (3 seconds = 1 speed rating point) ... My final speed ratings for Foot Locker have the NXN course running 18 seconds slower than the Foot Locker course for the boys ... IF anything, I suppose the NXN ratings for the boys could be a point higher, but the ratings posted are accurate.
Some General Information
Several viewers thought my Foot Locker ratings were too low compared to other years based on the final times of runners ... However, the Foot Locker course ran faster than normal in 2016 ... The Balboa Park course varies in speed more than most people realize ... I posted an article about this last year ("Footlocker at Balboa Park - Relative Speeds") ... The weather was ideal in 2016 ... and I suspect the footing and the mix of soil and grass (moisture content) was excellent as well based on the numbers ... For whatever reason, the course ran fast in 2016.
The girls' graph above shows that three girls separated themselves from everybody else ... Brie Oakley, Claudia Lane and Nevada Mareno ... That's what exceptional performances look like on a graph.