Rankings - statistical relevance?

[armandvanderMerwe]

Hi Guys

This is a question about how accurate the online rankings and times booked represents the indoor rowing population.

50 Years old. After a very successful whisky tour in Scotland last year I one day looked in the mirror, didn't liked what i saw and suddenly realize I am in a bit of trouble.
Bought my Concept in Jan 2014. Being rowing constantly the past few months according to the heart rate training program from Benson&Connolly. Dropped my weight from 83 to 73 Kg in 5 months. It is fun rowing.

My time over the 5k is around 22:19 and over the 2k around 8:20, making me a very average rower according to the online rankings. I am improving every week, and my aim is to hit the average time of the 2k and 5k for my age group in a month or two.

Now, the online rankings can have a way to be a bit disheartening if one look at the times being logged. In 2014 13 135 rowers logged their 2ktimes with an average of 8:05.

I would like to believe that the average indoor rower who logs time for rankings is probably a bit fitter, and maybe more obsessed with rowing than those who do not log their times.

I obviously understand that the definition of the indoor rowing population is contentious and wide open to interpretation. Does it include the casual rower at your local gym or not? Is it based on hours per week etc etc. There are around 21 000 forum members which gives you around 8 000 users who were inactive in 2014. Are they part of the population? Many top rowers do not log their times for rankings etc etc.

So the bottom line and simple question is: If one ranks around in the middle of the rankings for your age group (say 7:55) will it be a fair estimate to assume, that due to the average member profile of Concept 2 Online rankings, one will probably rank higher if one were able to estimate the broader indoor rowing population's average time?, or is this hypothesis nonsensical until one clearly defines the definition of the indoor rowing population ?

Armand

[Bob S.]

I think that using the rankings for anything other than just tracking your own progress is an exercise in futility. As you mentioned, many top rowers don't rank their results and there is no reason to expect them too. At the other end, it seems likely to me that there are many that would be too embarrassed to have their results in public view. I'm sure that there are a lot of erg users, especially in the gyms, who are not even aware of ranking or of keeping a logbook.

There are undoubtedly cheaters, but it is my optimistic hope that they are few and that their influence on the stats is insignificant.

Erg users are a very diverse group, ranging from enthusiasts with a lot of time available, churning out many millions of km a year, to those who have only occasional opportunities to use an erg. Some post their results in the rankings and many do not, for various reasons. Those that do post presumably post their best results of the season, but it is often just a single shot of a particular event, and not representative of the rowers capability. A lot of erg users rarely do the 10 events that can be ranked. For the most part, it is just those who are interested in competing who work on that rather limited list of events.

Your last phrase about clear definition gets to the point. I am convinced that it is impossible to clearly define the indoor rowing population.

Bob S.

[hjs]

Its double, yes the guys ranking are the ones who are more serious, but on the other hand the real top guys guys and most otw rowers don,t bother to rank anything.

[Hollywood_Kuma]

I've been working with and studying statistics for more than 30 years, so perhaps I can help with this.

Rowers are going to be much fitter than the average population. I'm told less than 10% of the UK population can run for 5k and, although I haven't verified that fact, it sounds eminently plausible.

Of the rowing population, people who track and post their times are going to be fitter than those who don't, because they take their rowing and fitness more seriously.

This is what statisticians and actuaries call "selection". We see it in insurance, where sick people are more likely to take out life assurance policies.

The fact that you can get on an erg and row for 5k without stopping probably puts you above median for the population as a whole, and certainly for men aged 50.

One could correlate fitness of rowers who post to rowers who don't post, and rowers who post to the general population, but it would be a lot of work.

Also, one has to take into account that some people have physiological advantages. My coach is >191 cm. I'm 180 cm. That obviously gives her an advantage. Age, weight and gender also impact. Pretty much anyone can row, but some people are just better built for the sport.

It's interesting (to a statistician at least) to see how skewed the data are. For my group and distance (5k heavyweight males, 40-49) the median time is 20:15.9, but the arithmetic mean time is more than 30 seconds slower, at 20:47.9. So, the people slower than the guy in the middle of the rankings are relatively slower than him to a greater extent than the extent to which the faster people are faster than him. If that makes sense.

Ultimately you should be proud with where you are, and what you can do, and try to improve. If you are ranked at number 900 out of 1,000 people, try to get to 890, and then to 880, and so on. We are not all the same, so the objective should be to do the best that you can possibly do. Desiderata probably gives the best advice, in rowing as in life:

"If you compare yourself with others, you may become vain and bitter; for always there will be greater and lesser persons than yourself".

You are already fitter than the average bear given what you can do now. Be proud of yourself, and aim to drag that time lower, perhaps setting yourself initially a goal of breaking 22:00. Then maybe target 21:45 and so on.

Best of luck.

[jamesg]

If we post distances in the erg logbook, we are by definition the Erg Community, especially if the distances include 5k and more. Those who do not post are either so fast that they are professional oarsmen, or know nothing about the logbook and don't row anyway, or at the very least can't reach 5k. Neither of these populations have anything to do with the Keep-Fit Pop (Erg Division).

Within the KFPE, we're all different (age, size, technique, stage, experience, habits, available time...) save for one thing: we move our carcasses.

Be happy if you're there, you're one of the 1% fittest on the planet, except maybe for Vietnamese and Chinese rice farmers and coolies.

Not only, you can, at a moment's notice, climb a mountain, swim a mile and back, cycle round your city or kayak round your lake. What more do we want, once the wife is happy?

[Bob S.]

Not only, you can, at a moment's notice, climb a mountain, swim a mile and back, cycle round your city or kayak round your lake.

Hah! In my dreams maybe. Just because I can climb onto my erg and dash off a few kms once in a while doesn't mean that I can do much of anything else. A walk (with a pair of canes) of less than 5 miles took me well over 2 hours today. I gave up cycling 5 or 6 years ago when a test run made me realize that I was a road hazard. My last swim was so long ago that I can't remember it at all. I don't know about kayaking but I wouldn't even trust myself in a recreational shell any more, let alone a race level shell. My sense of balance is shot. Fortunately, it is difficult to tip over an erg, even the rather high dynamic.

Bob S., whose get up and go got up and went.

[hjs]

Not only, you can, at a moment's notice, climb a mountain, swim a mile and back, cycle round your city or kayak round your lake.

Hah! In my dreams maybe. Just because I can climb onto my erg and dash off a few kms once in a while doesn't mean that I can do much of anything else. A walk (with a pair of canes) of less than 5 miles took me well over 2 hours today. I gave up cycling 5 or 6 years ago when a test run made me realize that I was a road hazard. My last swim was so long ago that I can't remember it at all. I don't know about kayaking but I wouldn't even trust myself in a recreational shell any more, let alone a race level shell. My sense of balance is shot. Fortunately, it is difficult to tip over an erg, even the rather high dynamic.

Bob S., whose get up and go got up and went.

Indeed, rowing is a very limited movement, yes I build endurence, but not speed, and rowers are notorious clumsy. Just like cyclists.

[jackarabit]

I saw Saeco pro racer Salvatore Commesso pick up a soft drink cup from the street with his mouth while warming up at one of the U.S Pro Championship satellite races in Wilmington DE in, IIRC, '99 or 2000. If he was clumsy it didn't show in his eye/lip coordination. Jack

[Bob S.]

Indeed, rowing is a very limited movement, yes I build endurence, but not speed, and rowers are notorious clumsy. Just like cyclists.

That is certainly a non-sequiter, hjs. My current limitations are all age-related, degenerative arthritis, loss of knee cartilage, flattened spinal disks, stenosis of the channel for the nerve to my left leg, failure of one of my arterial implants, extensive kyphosis resulting from osteoporosis, and gradual loss of my sense of balance - as well as macular degeneration, but that just interferes with reading.

Clumsiness might not matter much in erging, but rowing OTW is a different matter. The same goes for cycling. It doesn't matter much on a gym cycling machine, but out on the roads and trails, it would be a definite handicap.

For myself, I was always a lousy ball player, but that was a result of a combination of strong myopia and a high slow/quick twitch ratio. I suppose that some might regard clumsiness as being a natural consequence of a high slow/quick ratio, but it does not interfere with manual dexterity, just with quick reflexive action.

Bob S.

[hjs]

Indeed, rowing is a very limited movement, yes I build endurence, but not speed, and rowers are notorious clumsy. Just like cyclists.

That is certainly a non-sequiter, hjs. My current limitations are all age-related, degenerative arthritis, loss of knee cartilage, flattened spinal disks, stenosis of the channel for the nerve to my left leg, failure of one of my arterial implants, extensive kyphosis resulting from osteoporosis, and gradual loss of my sense of balance - as well as macular degeneration, but that just interferes with reading.

Clumsiness might not matter much in erging, but rowing OTW is a different matter. The same goes for cycling. It doesn't matter much on a gym cycling machine, but out on the roads and trails, it would be a definite handicap.

For myself, I was always a lousy ball player, but that was a result of a combination of strong myopia and a high slow/quick twitch ratio. I suppose that some might regard clumsiness as being a natural consequence of a high slow/quick ratio, but it does not interfere with manual dexterity, just with quick reflexive action.

Bob S.

My limitations are less age related, its mostly my back that is limiting me. So I can,t do mc in any sport, but on the erg I still can. I used to be very alround, not extremely good in anything, but usefull in everthing, also in ballsports, throwing, jumping etc. that all is gone.
Rowers, otw are clumsy, yes rowing is technical, but only in one very specific motion, if you have to choose between athletes, endurance athletes are the least versatile. Cyclist are proberly the most limited. No strenght, no speed, no flexibility. Only strong heart an lungs. Rowers are on top of that at least pretty strong.

[ArmandoChavezUNC]

Those who do not post are either so fast that they are professional oarsmen, or know nothing about the logbook and don't row anyway, or at the very least can't reach 5k.

You are leaving out a vast, vast number of people who use the erg/row. Very few collegiate oarsmen log their workouts, a good number of club oarsmen don't log their workouts, etc.

I would say there are WAY more regular erg/boat users who DO NOT log their workouts than those who do. And I would say it's inaccurate to say that they are all either elite or don't row anyway.

[hjs]

Those who do not post are either so fast that they are professional oarsmen, or know nothing about the logbook and don't row anyway, or at the very least can't reach 5k.

You are leaving out a vast, vast number of people who use the erg/row. Very few collegiate oarsmen log their workouts, a good number of club oarsmen don't log their workouts, etc.

I would say there are WAY more regular erg/boat users who DO NOT log their workouts than those who do. And I would say it's inaccurate to say that they are all either elite or don't row anyway.

Very true, looking a our nat. Championships, 1300 people did race, not even 5 % if those did rank anything. There alo seems to be a tendency to rank less, what more ways to report onrs training.
The crossfit movement also rows and I do see people sometime post video,s, but does people do not rank anything.
And in my lots of people row, most slow, but some do better, no one ever ranks anything.

Besides that, I don,t see the point in comparing with others that much, the concept is mostly an apparatus to compare you own improvements. And you know pretty well if you are well trained or are not so fit.

[Ralph Earle]

I’ve spent a lot of tedious time on this over the past week, so listen up!

I started with the 294 2K data from the 2014 rankings for 50-59 lightweights, because that distance has the most entries. I put the times into bins 17.5 seconds wide, because that is very close to the optimal value of 17.2 calculated using the Freedman-Diaconis rule.

The resulting frequency chart showed a so-called “contaminated” normal distribution of what I will call “serious” and “casual” ergers. For 2K times 7:22.5 and faster, a half-normal distribution with a mean of 7:22.5 and a standard deviation of 0:30.0 fit the data almost perfectly.

Given that excellent fit, I created a normal distribution with those parameters, and estimated the number of serious ergers in each frequency bin. For the seven bins from the mean bin to the fastest bin, the average difference between the predicted number of 2K times in that bin and the actual number was fewer than one per bin. The largest absolute differences were +3 and -3.

For the fifteen bins higher than the mean bin, I subtracted the number of serious ergers expected from the actual number to get the number of casual ergers in each bin. Only the first three of these fifteen bins were assumed to contain serious ergers. In these three bins, I assumed that the serious ergers had the fastest times in that bin. [I doubt that this created appreciable bias because the bin width was relatively small, 17.5 seconds. In the first mixed bin, 19 of 35 were assumed to be serious ergers. The average of the 19 fastest times in the bin was 7:48.8; the average of the remaining 16 times was 7:55.9, a 2% difference.] The net result was an estimated 93 “casual” ergers out of the total of 294, or 32%.

Here are the relevant percentiles of 2K times for the serious ergers, all ergers and the casual ergers:

%tile Serious All Casual
90% 6:47.1 7:01.2 7:55.8
75% 7:02.0 7:21.6 8:10.1
50% 7:19.9 7:45.0 8:37.2
25% 7:34.5 8:14.6 9:21.3

And here are the relative deviations from all ergers:

%tile Serious Casual
90% -3% +13%
75% -4% +11%
50% -5% +11%
25% -8% +13%

Thus, to answer Mr. vanderMerwe’s primary question, to compare yourself to the “average member profile” simply increase the overall percentiles by 12%. For example, last season the 50th percentile for 50-59 male lightweight 5Ks was 20:18.6; add 12% and you get 22:44.8, so Mr. vanderMerwe’s 22:19 is “above average” (“above median,” actually).

[Pause for a reality check: in 2014 a 5K of 22:44.8 would have ranked 237th out of 283. If my model is correct, there would have been 2*(283-237)-1 = 91 “casual” ergers out of the total of 283, or 32%. How about that!]

“OK, smarty-pants – what about all the ergers who didn’t rank a 2K? How do you know they wouldn’t be much slower (which is perhaps why they don’t rank one)?”

Well, what do we know about them? Many participate in the Annual Meters Honor Board, so I laboriously identified all 50-59 male lightweights in the 2014 Board with daily average meters of 2,500 or more. (I did not extract from the 1,500-2,499 group – checking the profiles of 2,236 was just more than I wanted to take on. But I did not ignore them, as you will see.)

Now most people – most ergers, anyway – believe that the more meters you erg, the faster you get. And, in fact, an analysis of the 2K times for 75 ergers who were on the Annual Meters Honor Board confirmed this. (This time I did include the 1,500-2,499 category). Among these 75, an additional 1,000 meters per day corresponded to a 6.5-second decrease in 2K time, a reasonable and practical benefit.

So let’s compare average meters per day of the ergers who don’t post 2K times with the average of the ergers who do. Surely the ergers who don’t post will turn out to log considerably fewer meters per day. And from the analysis of the 75 we can estimate what the non-posters’ average time would be.

Well, guess what: the non-posters averaged 4,968 m/day, while those who ranked a 2K averaged 5,295 m/day. Those extra 309 meters predict a 2K time of 7:24.7 versus 7:26.1 for the non-posters, about 0.3%. Oops, nothing to see here, folks!

“Wait a minute – you said you didn’t look at the 2,236 people on the Board with 1,500-2,499 meters per day. Surely their 2Ks would be a lot slower!” OK, let’s look at the 27 ergers who posted a 2K and who erged only 1,500-2,499 m/day. Their median meters per day was 1,966. The median meters per day for all people in that group – male and female, heavyweight and lightweight –was 1,920 m/day. Those extra 46m/day were worth just two-tenths of a second off a 2K time. Nothing to see here either, I’m afraid.

“Wait, wait, wait,” says the sole surviving stats-geek-reader of this epic post. “You left out the largest and potentially most important group, the ‘8,000 users who were inactive in 2014’!”

Well, you got me there. But, as Yogi Berra once said about dwindling attendance, “If they don’t want to come, how you gonna stop ‘em?” I think we can safely exclude them and redefine the “population” as those who care enough to log at least 1,500m/day.

[gregsmith01748]

This is really great work! I read it to the end.

I think your division into serious and casual is spot on.

[Ralph Earle]

Thank you. I especially appreciate your response, coming as it does from one who, in addition to being an accomplished sculler, also pays close attention to what the numbers have to offer.