i59: Working the Dream

Blue Skies Magazine November 2014 cover

It’s alive! Our November issue is mailing out now to current subscribers. If you are not a current subscriber, you can change that right here, right now.

Please give it until December 1 for the postal service to get your mag to you. If you still don’t have it by then, let us know by emailing Kolla at kolla@blueskiemag.com and she’ll get you sorted.

Blue Skies Magazine November 2014 cover

i59: November 2014 | Marco Waltenspiel competing in the accuracy event during Skydive PINK Klatovy’s Pink Canopy Piloting Open 2014. Photo by Wolfgang Lienbacher, lienbacher.com.

On the Cover

Wolfgang Lienbacher catches Marco Waltenspiel touching down in the touchiest round of CP competition, accuracy. Sydney Owen Williams discusses one of the favored topics for all newbies: quitting your job to skydive full-time.

N00bs, the industry needs more young energy and fresh ideas to keep it progressing. If you want to be an instructor and aren’t totally scared off by the reasons not to work in the sport, then start talking to instructors and jumpers you trust. Get some sound advice about the path you should take to getting your ratings, then go forward with enthusiasm!

Featured Photo

Saying goodbye to warm temperatures in the northern hemisphere. Julie Kleinwort and Shaggy Isaacson over Chicagoland Skydiving Center. Photo by Javier “Buzz” Ortiz.

The FlyBy

  • Reader Question: What are you most thankful for?
  • Comic Relief: Take It DZ by Nadene Beyerbachadventurecreative.ca
  • Monthly tit4tat, tit4tatcanda.com
  • Skydive Chicago’s Rookiefest by Hillary Hmura
  • Skydive Temple’s Deadman Boogie by Wendy Faulkner
  • BSBD, Eldon Burrier: A tribute by Dennis Swift

Pictorial

Skydive Pink Klatovy’s Pink Canopy Piloting Open 2014 Photo Essay by Wolfgang Lienbacher, lienbacher.com. Wolfgang captures the agony, the ecstasy and the pink at Klatovy.

Get the Shot by Randy Swallows

Super cool new feature alert! Photographers will tell you, in detail, how they “got the shot” so you can go out, recreate and develop your own style and technique. This month, Randy Swallows, randyswallows.com, talks about the fish-eye lens.

Fish-eye lenses can be used for so much more than just fitting everything in the shot.

Girls Just Wanna Get Flying by Annette O’Neil

The cleverest ginger interviews Paloma Granero, one of the best tunnel flyers in the world. Why *are* there so few female tunnel instructors, anyway?

The “girls-can’t-instruct-safely-in-the-tunnel” myth is one that cries out for busting, and one of the best arguments against it is Paloma Granero.

Blue Skies Mag i59, Super Sky SleuthSuper Sky Sleuth

Original by the fucking legend that is Maccawww.MaccaDigital.com. If you didn’t find all 10, answers can be found here:Super Sky Sleuth Solved! Let me know what you think of this, too – love it and want more? Hate it and want less?

Centerfold

That Swallows guy again! He got another shot, of 8-way FS team Qatar Falcons at Nationals.

They were a guest team but would have taken second in intermediate with an 8-point average.

SkyCouples: Scott & Crystal by Eli Godwin

Did you miss SkyCouples? Eli Godwin is back with the cutest dual-aerial couple yet, Scott and Crystal. (That Crystal!)

I think a lot of my male skydiver friends wish that Scott was their boyfriend!

We’re Creating Quitters by James La Barrie

Seriously, if you run or manage a drop zone and haven’t subscribed to James La Barrie‘s newsletter and/or read his column and/or hired him to help you, well I just don’t know. This month he tackles the waiting game we make students go through. The game that’s so ingrained that I hadn’t even questioned it until reading his column.

If a student is riding the fence about whether to become a skydiver or not, they’ll probably fall on the wrong side nearly every time. It’s as if we test those entering the sport by saying, “How bad do you really want it?” Only the hardest of the diehards, the ones bitten so badly by the sport that they can’t live without it, make it through.

Go with the Flow by Fred Olsen

Fred Olsen learned something on a river in Maine that will help you be a better skydiver. True story.

There’s nothing more frustrating as a beginner than trying to stuff 240 square feet of nylon into what seems the smallest bag that someone was capable of making. The harder I try, the larger it gets. The Zen just escapes.

Turning Points: New FS World Order by Kurt Gaebel, NSL

You used to be able to predict with decent certainty who would win, but some countries are intent on throwing spanners into the works. Kurt Gaebel, National Skydiving League, discusses who stands where and why the cats are sleeping with the dogs.

Belgium is only the fifth country since 1985 that has won a gold medal in any formation-skydiving competition event.

Read the full article online at skyleague.com.

The Way of the Jump Pilot by the Fuckin’ Pilot

We Dean “Princess” Ricci. Lest you be distracted by the poop and sex and porn stories, he is an actual jump pilot. This month he rounds up a bunch of his fellow pilots to talk about why they keep taking us up to altitude.

Nowhere else in flying does a pilot have to learn to deal with a shifting load of crazy jumpers, but passengers who leave halfway through the trip—all while making sure passengers exit in exactly the right spot, at exactly the right altitude and at the perfect speed every single time.

Coming Home by Melanie Curtis

As always, we save the best for last. Your monthly dose of sanity, mindfulness, LTD and Blue Steel is here! So we all know the roller-coaster adrenaline and excitement of life is the ish, but you know that feeling after, when it’s all over? That’s the “aaaaah” Melanie Curtis, melaniecurtis.com, is relishing this month.

Feeling the comfort of coming back to where you came from, connecting with your own story, your own values as an essential preparation before firing your own engines back up and forging ahead.

Dear SkyGod

Super Sky Sleuth

Blue Skies Mag i59, Super Sky Sleuth

If you got your November issue, did you notice our new little ‘find the difference’ game, featuring a photo by ‘the fucking legend that is Macca‘? Do you love it, hate it, don’t care, want more, never want to see it again? Let me know! Email lara@blueskiesmag.com or comment.

More importantly, did you find all the differences? (Clicky makes it full-screen)

Blue Skies Mag i59, Super Sky Sleuth

Did you find all 10 differences?

Strike that, reverse it

DataWrangler

When I said I’m not a data scientist, I meant it. My last chart-happy post about male versus female confidence in skydiving was heavy on pretty graphs and light on actual data analysis. Fearless reader – and actual data scientist – Clifford Richardson ran the data through some heavy-duty industrial grinders and come up with a bit more rigorous work through.

Long story short, (TL;DR): “In short conclusion, freefall confidence isn’t statistically different between genders, canopy flight confidence seems to be, and females and males are equally varied in the amount of jumps it takes to get comfortable under that patchwork of life-saving nylon.”

And for the true stats lovers, here is the full explanation. Huge thanks and kudos to Clifford!


Synopsis of Skydiving Confidence Data

by Clifford Richardson

In response to the recent article about confidence in skydiving, I have taken the raw data and given it a more in-depth analysis to help make a proper conclusion. I use some common statistical tests and terms to make some formal conclusions, but I will explain the purposes behind them for those who are not mathematically inclined. I apologize in advance for the lengthy wording. I write for scientific communities and the boring prose is all I know.

First, I wanted to address the main question: Is there a statistical difference between men and women when looking at confidence for either canopy or freefall flight?

To examine this question, let’s look at the original survey questions:

  1. Male or Female?
  2. I felt confident in my canopy-flying and canopy-landing skills at jump #___.
  3. I felt confident in my freefall skills at jump #___.

Male or female is an easy answer to interpret. However, I wanted to compare solid “yes/no” answers to determine if that answer is dependent on gender (I’ll get into the reason for this in the next paragraph). Therefore I interpreted non-ambiguous numerical answers to questions 1 and 2 to mean that the jumper is now confident in their abilities. Ambiguous answers that could have meant yes or no were dropped from the data set; there were only 4 instances where this was the case.

Now that I had the data reported in a file the way I wanted it, I used a powerful computing program called “R” to perform a chi-squared (χ2) test on tabulated data. I know we all like graphics, but there are no fancy graphs for this portion of the analysis. We do have a table of the categorical data for confidence in both canopy and freefall skills (Tables 1 & 2).

The chi-squared test for non-parametric (categorical) analysis determines if one categorical variable is dependent on another, i.e. whether confidence depends on gender. If the p-value is less than or equal to 0.05, we are at least 95% certain that the two variables are dependent on each other. The value is just an arbitrary limit that statisticians decided was good enough to consider “statistically significant.” I promise I’m not just making this up as I go along. The benefit of the chi-squared test is that sample size doesn’t have a strong adverse effect on the test. The fact that more respondents were male is accounted for.

Confident Not Confident
Male 197 6
Female 68 14

Table 1: Confidence versus Gender for Canopy Flight.
Numbers represent the number of respondents that fit the table criteria.
Pearson’s chi-squared p-value=7.259e-05.

Confident Not Confident
Male 195 6
Female 79 5

Table 2: Confidence versus Gender for Freefall Flight.
Numbers represent the number of respondents that fit the table criteria.
Pearson’s chi-squared p-value=0.3962.

Confidence isn’t gender dependent for freefall skills, but appears to be gender-dependent for canopy flight.

Confidence isn’t gender dependent for freefall skills, but appears to be gender-dependent for canopy flight. However, we cannot say it is only due to gender with great certainty; we can only say that based on this data set, we see with over 99% certainty that gender has an effect on canopy flight confidence. This doesn’t account for other possible factors such as type of instruction, age, etc. This is why surveys are hard to infer concrete conclusions from, but in situations like this it is the best way to collect data because we don’t want to experiment on people in skydiving (throwing an inexperienced jumper under a high performance canopy to test their canopy skills is frowned upon). We must reduce the number of confounding factors and the only way to do that is to collect data relevant to those possible confounding variables. Survey analysis is really a chess game.

Should I stop there? No. I want to give as much effort as possible to this since Blue Skies Mag deserves it for collecting the data and making each datum available (free information is a blessing). I will however, make a calculated effort. For instance, because I saw that based on the simple chi-squared test that freefall skills and gender are statistically non-interdependent, there is no reason to pursue further analysis. The canopy flight skills I did, however.

Bear with me, because the following involves more complicated stuff. Things like probability distributions, probability density functions, and some fancy stats tests. So, we have something cool available to us: the number of jumps it took for a jumper to be confident in their canopy skills.

Right, so why is this cool? Well, because we can model both the male and female data by a probability function and compare the two models to see if males get confident in canopy flying sooner than females or vice versa. Fitting a probability distribution to the data is extremely important because it gives hints as to what tests we can perform to compare the two data sets and in some cases is mandatory for the tests. There are cheap and easy ways around this (the Kruskal-Wallis test for instance), but doing a little more work is better in my opinion. The simplest form of model fitting is linear regression. Add in some special parameters based on probability theory and you get more complicated, but useful equations that can describe your data. These are what probability density functions are. Because fitting more complicated models is, for lack of a better word, complicated … I let R do all the work for me by using a function to fit different distributions and seeing which fit best.

I am pretty comfortable with reading data, so I knew the best bet for this data would be the Weibull distribution. However, because I can’t just assume, I ran a validation test for “goodness of fit.” The test is called the Anderson-Darling test. The reason I chose this test is because of its sensitivity to skewed (tail skewed, not “cheezed” skewed) data. You can Google the details, but for validating Weibull distributions, it is fantastico. You can see the results below (Figures 1, 2, & 3).

Unlike the chi-squared test, the Anderson-Darling test p-value tries to test for independence. A p-value of less than or equal to 0.05 means the distribution does not fit. We want to see a value higher than 0.05.

Time to Canopy Flight Confidence | Blue Skies Mag

Figure 1: Histogram of the number of jumps until canopy flight confidence was attained by females in the sample population. The number of jumps was equally divided into 50 bins. A Weibull probability distribution was fitted to the model with parameters estimated to maximum likelihood. The shape and scale parameters are 0.8583 (±0.0740) and 204.6635 (±30.6800) respectively. An Anderson-Darling test was performed to determine goodness of fit (p-value: 0.3053).

Time to Canopy Flight Confidence | Blue Skies Mag

Figure 2: Histogram of the number of jumps until canopy flight confidence was attained by males in the sample population. The number of jumps was equally divided into 50 bins. A Weibull probability distribution was fitted to the model with parameters estimated to maximum likelihood. The shape and scale parameters are 0.8602 (±0.0458) and 142.9110 (±12.5089) respectively. An Anderson-Darling test was performed to determine goodness of fit (p-value: 0.0813).

Time to Canopy Flight Confidence | Blue Skies Mag

Figure 3: Histogram of the number of jumps until canopy flight confidence was attained by both genders in the sample population. The number of jumps was equally divided into 50 bins. A Weibull probability distribution was fitted to the model with parameters estimated to maximum likelihood. The shape and scale parameters are 0.8396 (±0.0380) and 155.7915 (±12.0613) respectively. An Anderson-Darling test was performed to determine goodness of fit (p-value: 0.0628).

What this tells me is that the models are adequate for the pooled data, and the data separated by gender. The next step is to perform log-likelihood tests on each model. I’m going to save some time and let you trust me on the values. Then the chi-squared distribution is used to calculate what’s known as the maximum likelihood ratio. It’s a way to analyze two models to see if it’s more likely that the data could have come from the model of the gender-separated data or the non-gender-separated data. It is not the same kind of result we calculated before using chi-squared, and instead a p-value of greater than 0.05 means that the differences in the data that we see are most likely just random and there’s no real dependence in gender.

Jumping to the result, I got a p-value of 0.9002. So are males becoming more confident under canopy quicker than females? No, not according to the data.

TL;DR

In short conclusion, freefall confidence isn’t statistically different between genders, canopy flight confidence seems to be, and females and males are equally varied in the amount of jumps it takes to get comfortable under that patchwork of life-saving nylon.

I recommend further investigation based on other surveys that build on top of this one. Future questions should include as wide of a range of factors as possible, including total jumps, age, type of instruction, years in the sport, number jumps in the last 30 days, and if the jumper has been involved in an incident that led to injury in both freefall and canopy flight. Big time acknowledgments to Blue Skies Mag for getting this stuff into the open for investigation.

Clifford Richardson

Data Wrangler

About the author: “I worked as a biologist in New Mexico for 4 years catching wild animals, testing cancer and antimicrobial drugs, and analyzing research data. Got my skydiving license (A-71041) in July of this year and haven’t gone back to biology since. Now I live in California where I do whatever job pays to get money to spend on my next gear rental fee and lift ticket. Favorite color: red.”

Happy voting day!

DZawards

Hey Americans, did you vote today? You totally should. Participation is the bedrock of democracy. And,

Vote, for fuck's sake!

When you get back from your polling place, also remember to vote in this year’s Drop Zone Awards. We love bestowing glory and riches on all the DZs that worked hard and did it right this year.

Note: You may also vote directly at https://blueskiesmag.typeform.com/to/az5ylX.

November 7, 2014: Voting is now closed! Look for the results in the December 2014 issue of Blue Skies Mag.

Help a Jumper Out: Glenn Williams

http://www.youcaring.com/medical-fundraiser/glenn-s-membership-to-the-metal-club/255696

Glenn Williams, a jumper from Massachusetts, was visiting Tsunami Skydivers last weekend when he had a fairly serious accident resulting in a broken femur and pelvis. His friend Matthew wrote in to tell us, “One of our awesome skydive peeps recently had a pretty serious skydiving accident while visiting Oceanside and I’m trying to help him and his girlfriend by running a fundraiser to help with the burdens and costs as they deal with the hard road to recovery.”

Glenn and his girlfriend Erica were with a group of other skydivers visiting California to attend another skydiver’s wedding. His home DZ is Connecticut Parachutists, Inc. (CPI) and he also jumps at Pepperell and Jumptown in Orange, Mass.

So if you have a few bucks ready to deposit in the karma bank, help Glenn out at the fundraising site his friends have set up: www.youcaring.com/helpglenn.

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