Raw data vs C2 log graph & summaries (ErgData)

[msongy]

The raw data CSV data does not match the logbook graphs, nor the interval summaries. I created a workout with 500m/undefined rest intervals and rowed 7 intervals. The first interval - a 500m warmup - took 2:28, but data collection continued past 500m - four data points past 500 (and later seven points past 500m - and I guarantee you I stopped pulling at 500m!). That first interval was summarized as a 3:12 split! Not 2:28! And the average stroke rates are all over the place.

Are there tutorials or white papers discussing the mechanics and definitions behind data collection and interpretation by the both ErgData and the PM5 algorithms? The ErgData log on my phone shows these same summaries, so I don’t think it has anything to do with the C2 log site, however, pace/SR graphs on C2 Log site reflect these same inaccuracies - and then some!

I’m using a PM5 and ErgData on an IPhone 6s.

P.S. what means of data recording provides the most detail in terms of both number of data categories as well as sample rate? Does any means of data recording capture pure sensor readings at an adjustable sample rate? Does ErgData simply collect, display and record data from the PM5, or does it perform any calculations itself? Does the PM5 actually record raw data, and if so, at what sample rate? Is the catch electro-mechanically triggered, or is it interpolated using data patterns? I guess that covers most of WHY I want to see the white papers...

[jamesg]

My old C has three magnets on the flywheel delivering one impulse every 3 cm chain movement, at 50-60 Hz. Not quite an industrial encoder with 1000 impulses per turn. I've heard that data out can't be better than data in. Ergdata has 20% errors that can be seen by doing some sums.

WGAD, it all gets me fit anyway.

[sbouaoud]

Did you ever get answers anywhere regarding a white paper that would explain all this?
I have also noticed some strange things in the stroke data CSV files where pace numbers and stroke rates don't match the time and distance data. It seems for one thing the time stamps in the file are rounded but hopefully the pace data is based on unrounded readings and we just don't see them.
Has anyone corresponded to C2 on this already?

[Citroen]

Don't hold your breath waiting for a reply from msongy, he/she hasn't logged into the forum since Thu 27 Feb 2020, 18:45.

Most folks sync their data from Ergdata to their online log at https://log.concept2.com/log which gives you some pretty graphs and the ability to download your data as CSV or TCX or FIT formats.

[msongy]

Did you ever get answers anywhere regarding a white paper that would explain all this?
I have also noticed some strange things in the stroke data CSV files where pace numbers and stroke rates don't match the time and distance data. It seems for one thing the time stamps in the file are rounded but hopefully the pace data is based on unrounded readings and we just don't see them.
Has anyone corresponded to C2 on this already?

Sorry about that, and not really. I did ask a couple of different questions and was told something like, ‘good point/idea. I’ll submit it to the analytics team,’ but haven’t heard much beyond that, and I let it fall off my radar while I concentrated on more gestalt-ish metrics and my own biokenitics. It’s hard to care about fine tuning data analysis while my left bicep tendons are singing “We’re Not Gonna Take It!”

One thing I never did, however, was look into the data systems on the other top ergs to compare. However, I’m not interested in buying a different erg, and have honestly found little personal value in pursuing perfection with my C2 data. However, I always keep my ear to the ground.

[sbouaoud]

Thank you msongy
I will lob in an email to them and see what they say and report back if I get the answers

[sbouaoud]

Don't hold your breath waiting for a reply from msongy, he/she hasn't logged into the forum since Thu 27 Feb 2020, 18:45.

Most folks sync their data from Ergdata to their online log at https://log.concept2.com/log which gives you some pretty graphs and the ability to download your data as CSV or TCX or FIT formats.

Thank you and that is exxactly what I have been doing but the data in the files is either way off, very imprecise or has a hidden logic which I am not aware of.

[Citroen]

Don't hold your breath waiting for a reply from msongy, he/she hasn't logged into the forum since Thu 27 Feb 2020, 18:45.

Most folks sync their data from Ergdata to their online log at https://log.concept2.com/log which gives you some pretty graphs and the ability to download your data as CSV or TCX or FIT formats.

Thank you and that is exxactly what I have been doing but the data in the files is either way off, very imprecise or has a hidden logic which I am not aware of.

Send a message to Concept2 from https://log.concept2.com/contact and ask them to investigate your data anomalies.

[Carl Watts]

It can be too easy to get carried away with the data instead of the actual rowing. There really isn't anything to worry about with the PM5 and ErgData but it would appear that the availability of more data can just cause problems for some people. If you go back to the PM1 and the PM2, all you had was what was on the monitor and really all the critical performance related stuff was still there back in 1986.

Ergdata is great for the Logbook syncronisation and a better verification system and some cool looking graphs if you use a heartrate monitor as well, its all most people need. Works well for me.

[sbouaoud]

It can be too easy to get carried away with the data instead of the actual rowing. There really isn't anything to worry about with the PM5 and ErgData but it would appear that the availability of more data can just cause problems for some people. If you go back to the PM1 and the PM2, all you had was what was on the monitor and really all the critical performance related stuff was still there back in 1986.

Ergdata is great for the Logbook syncronisation and a better verification system and some cool looking graphs if you use a heartrate monitor as well, its all most people need. Works well for me.

To each their own and I understand that the system has worked very well for many years and many people. I like to be able to dig deeper into things and since there is data available I would like to know if it is good enough and how to interpret it in order to go beyond the available analysis. Also in some situations a fraction of a stroke or second can make a difference.

[msongy]

It can be too easy to get carried away ...

To each their own ...

Based on everything I’ve learned about the data system and collection hardware, what exists now provides the majority of rowers enough data with acceptable accuracy. Significantly improving the accuracy would require far more electro-mechanical triggers in order to shorten the “distance” between data points. Our graphs and results are, in essence, pixelated, but clear enough to render what most consider to be a clear-enough picture.

I can’t say with any degree of certainty that the existing algorithms can be improved, but I’m betting C2 reached a point of diminishing returns while figuring that out. Nonetheless, like you, I’m still curious, but at the end of the day, it’s still not going to help me PR.