sun, 04-aug-2013, 09:35

How will I do?

My last blog post compared the time for the men who ran both the 2012 Gold Discovery Run and the Equinox Marathon in order to give me an idea of what sort of Equinox finish time I can expect. Here, I’ll do the same thing for the 2012 Santa Claus Half Marathon.

Yesterday I ran the half marathon, finishing in 1:53:08, which is an average pace of 8.63 / 8:38 minutes per mile. I’m recovering from a mild calf strain, so I ran the race very conservatively until I felt like I could trust my legs.

I converted the SportAlaska PDF files the same way as before, and read the data in from the CSV files. Looking at the data, there are a few outliers in this comparison as well. In addition to being ouside of most of the points, they are also times that aren’t close to my expected pace, so are less relevant for predicting my own Equinox finish. Here’s the code to remove them, and perform the linear regression:

```combined <- combined[!(combined\$sc_pace > 11.0 | combined\$eq_pace > 14.5),]
model <- lm(eq_pace ~ sc_pace, data=combined)
summary(model)

Call:
lm(formula = eq_pace ~ sc_pace, data = combined)

Residuals:
Min       1Q   Median       3Q      Max
-1.08263 -0.39018  0.02476  0.30194  1.27824

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -1.11209    0.61948  -1.795   0.0793 .
sc_pace      1.44310    0.07174  20.115   <2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.5692 on 45 degrees of freedom
Multiple R-squared: 0.8999,     Adjusted R-squared: 0.8977
F-statistic: 404.6 on 1 and 45 DF,  p-value: < 2.2e-16
```

There were fewer male runners in 2012 that ran both Santa Claus and Equinox, but we get similar regression statistics. The model and coefficient are significant, and the variation in Santa Claus pace times explains just under 90% of the variation in Equinox times. That’s pretty good.

Here’s a plot of the results:

As before, the blue line shows the model relationship, and the grey area surrounding it shows the 95% confidence interval around that line. This interval represents the range over which 95% of the expected values should appear. The red line is the 1:1 line. As you’d expect for a race twice as long, all the Equinox pace times are significantly slower than for Santa Claus.

There were fewer similar runners in this data set:

2012 Race Results
Runner DOB Santa Claus Equinox Time Equinox Pace
John Scherzer 1972 8:17 4:49 11:01
Greg Newby 1965 8:30 5:03 11:33
Trent Hubbard 1972 8:31 4:48 11:00

This analysis predicts that I should be able to finish Equinox in just under five hours, which is pretty close to what I found when using Gold Discovery times in my last post. The model predicts a pace of 11:20 and an Equinox finish time of four hours and 57 minutes, and these results are within the range of the three similar runners listed above. Since I was running conservatively in the half marathon, and will probably try to do the same for Equinox, five hours seems like a good goal to shoot for.

sat, 27-jul-2013, 08:03

Gold Discovery Run, 2013

This spring I ran the Beat Beethoven 5K and had such a good time that I decided to give running another try. I’d tried adding running to my usual exercise routines in the past, but knee problems always sidelined me after a couple months. It’s been three months of slow increases in mileage using a marathon training plan by Hal Higdon, and so far so good.

My goal for this year, beyond staying healthy, is to participate in the 51st running of the Equinox Marathon here in Fairbanks.

One of the challenges for a beginning runner is how pace yourself during a race and how to know what your body can handle. Since Beat Beethoven I've run in the Lulu’s 10K, the Midnight Sun Run (another 10K), and last weekend I ran the 16.5 mile Gold Discovery Run from Cleary Summit down to Silver Gulch Brewery. I completed the race in two hours and twenty-nine minutes, at a pace of 9:02 minutes per mile. Based on this performance, I should be able to estimate my finish time and pace for Equinox by comparing the times for runners that participated in the 2012 Gold Discovery and Equinox.

The first challenge is extracting the data from the PDF files SportAlaska publishes after the race. I found that opening the PDF result files, selecting all the text on each page, and pasting it into a text file is the best way to preserve the formatting of each line. Then I process it through a Python function that extracts the bits I want:

```import re
""" lines appear to contain:
place, bib, name, town (sometimes missing), state (sometimes missing),
birth_year, age_class, class_place, finish_time, off_win, pace,
points (often missing) """
fields = line.split()
place = int(fields.pop(0))
bib = int(fields.pop(0))
name = fields.pop(0)
while True:
n = fields.pop(0)
name = '{} {}'.format(name, n)
if re.search('^[A-Z.-]+\$', n):
break
pre_birth_year = []
pre_birth_year.append(fields.pop(0))
while True:
try:
f = fields.pop(0)
except:
print("Warning: couldn't parse: '{0}'".format(line.strip()))
break
else:
if re.search('^[0-9]{4}\$', f):
birth_year = int(f)
break
else:
pre_birth_year.append(f)
if re.search('^[A-Z]{2}\$', pre_birth_year[-1]):
state = pre_birth_year[-1]
town = ' '.join(pre_birth_year[:-1])
else:
state = None
town = None
try:
(age_class, class_place, finish_time, off_win, pace) = fields[:5]
class_place = int(class_place[1:-1])
finish_minutes = time_to_min(finish_time)
fpace = strpace_to_fpace(pace)
except:
print("Warning: couldn't parse: '{0}', skipping".format(
line.strip()))
return None
else:
return (place, bib, name, town, state, birth_year, age_class,
class_place, finish_time, finish_minutes, off_win,
pace, fpace)
```

The function uses a a couple helper functions that convert pace and time strings into floating point numbers, which are easier to analyze.

```def strpace_to_fpace(p):
""" Converts a MM:SS" pace to a float (minutes) """
(mm, ss) = p.split(':')
(mm, ss) = [int(x) for x in (mm, ss)]
fpace = mm + (float(ss) / 60.0)

return fpace

def time_to_min(t):
""" Converts an HH:MM:SS time to a float (minutes) """
(hh, mm, ss) = t.split(':')
(hh, mm) = [int(x) for x in (hh, mm)]
ss = float(ss)
minutes = (hh * 60) + mm + (ss / 60.0)

return minutes
```

Once I process the Gold Discovery and Equnox result files through this routine, I dump the results in a properly formatted comma-delimited file, read the data into R and combine the two race results files by matching the runner’s name. Note that these results only include the men competing in the race.

```gd <- read.csv('gd_2012_men.csv', header=TRUE)
gd <- gd[,c('name', 'birth_year', 'finish_minutes', 'fpace')]
eq <- eq[,c('name', 'birth_year', 'finish_minutes', 'fpace')]
combined <- merge(gd, eq, by='name')
names(combined) <- c('name', 'birth_year', 'gd_finish', 'gd_pace',
'year', 'eq_finish', 'eq_pace')
```

When I look at a plot of the data I can see four outliers; two where the runners ran Equinox much faster based on their Gold Discovery pace, and two where the opposite was the case. The two races are two months apart, so I think it’s reasonable to exclude these four rows from the data since all manner of things could happen to a runner in two months of hard training (or on race day!).

```attach(combined)
combined <- combined[!((gd_pace > 10 & gd_pace < 11 & eq_pace > 15)
| (gd_pace > 15)),]
```

Let’s test the hypothesis that we can predict Equinox pace from Gold Discovery Pace:

```model <- lm(eq_pace ~ birth_year, data=combined)
summary(model)

Call:
lm(formula = eq_pace ~ gd_pace, data = combined)

Residuals:
Min       1Q   Median       3Q      Max
-1.47121 -0.36833 -0.04207  0.51361  1.42971

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept)  0.77392    0.52233   1.482    0.145
gd_pace      1.08880    0.05433  20.042   <2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.6503 on 48 degrees of freedom
Multiple R-squared:  0.8933,    Adjusted R-squared:  0.891
F-statistic: 401.7 on 1 and 48 DF,  p-value: < 2.2e-16
```

Indeed, we can explain 65% of the variation in Equinox Marathon pace times using Gold Discovery pace times, and both the model and the model coefficient are significant.

Here’s what the results look like:

The red line shows a relationship where the Gold Discovery pace is identical to the Equinox pace for each running. Because the actual data (and the prediced results based on the regression model) are above this line, that means that all the runners were slower in the longer (and harder) Equinox Marathon.

As for me, my 9:02 Gold Discovery pace should translate into an Equinox pace around 10:30. Here are the 2012 runners who were born within ten years of me, and who finished within ten minutes of my 2013 Gold Discovery time:

2012 Race Results
Runner DOB Gold Discovery Equinox Time Equinox Pace
Dan Bross 1964 2:24 4:20 9:55
Chris Hartman 1969 2:25 4:45 10:53
Mike Hayes 1972 2:27 4:58 11:22
Ben Roth 1968 2:28 4:47 10:57
Jim Brader 1965 2:31 4:09 9:30
Erik Anderson 1971 2:32 5:03 11:34
John Scherzer 1972 2:33 4:49 11:01
Trent Hubbard 1972 2:33 4:48 11:00

Based on this, and the regression results, I expect to finish the Equinox Marathon in just under five hours if my training over the next two months goes well.

sun, 27-jul-2008, 14:23

the swimming hole

Once again, I’ve neglected my blog. My new job, the pressures of getting all our work done this summer, and the rest of life has kept me away.

Events: We’ve taken to swimming in the Creek. During the warmth of early June (which hasn’t returned since…) the Creek temperature rose to 65°F, and swimming was actually quite nice. I’m hoping we’ll get a few more warm days before fall so we can swim out there again.

Projects: I’ve made no progress at all on the new shed, but have repaired the bridge and got our digital antenna installed on the roof. I also replaced our chimney cap with the variety our chimney sweep prefers. Things left to do: Build the shed!, repair the glycol line that keeps the septic pipe thawed, fix and insulate the sewage treatment plant discharge pipe, reinforce the shed roofs, obtain and chop two more cords of firewood, install a heat shield behind the wood stove, get curtains for the two large downstairs windows and the sliding glass doors, and (finally) consider hiring a plumbing and heating company to replace and upgrade our system.

Books: I’ve read quite a few. Here’s a summary judgement on each:

• McSweeney’s Quarterly Concern, Volume 26: Enjoyable fictions, interesting format, no real standouts for me.
• The Rest is Noise: Fantastic look at the music and history of the 20th century. Alex Ross is one of my favorite New Yorker writers and this book doesn’t disappoint.
• Ambitious Brew: Interesting history of beer brewing in the United States. It dispels many of the classic beer myths (the most classic being that the big super-brewers ruined American beer, only to be “saved” by the micros), and tells a great story. Prost!
• Let the Northern Lights Erase Your Name: A very enjoyable book with a very memorable female lead. Vida has a great abbreviated and expressive way of writing that was refreshing.
• The Echo Maker: I’ve been looking forward to this one for so long, that I think the reading of it couldn’t be anything but a disappointment. I enjoyed it as a meditation on brain injury, but I felt like the characters were a little overwrought and stiff.

The rest: Andrea continues to progress toward her goal of running the Equinox Marathon. She’s out running sixteen miles (16 miles!) right now. I’m super proud of her. Meanwhile, I’ve been bicycling to work almost every day (13 miles round-trip) and the two of us are working toward doing 100 push ups in six weeks. Maybe by the next photo of me in the Creek, I’ll be ripped.

Probably not…

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