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PETE'S ERRORS WITH PROTEGE
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Picture of Neville
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Pete:
You said the other day that you were comfortable with the electronic counter, but now you say that you are not confident in your data and the Protégé reduces your ability to concentrate on the measurement. You could improve your comfort dramatically by making the following changes to your version of the method:

1. Use only one magnet instead of four: You do not have to be a statistician to realize that if there is a possible problem with one magnet it is four times greater with four.

2. Make one continuous or near-continuous ride of the course: No problems are possible with the counter while riding as is the case when making stops. If the continuous ride and that with stops to mark splits agree well as to the course length, this is evidence that no errors have occurred.

Below are some of my comments on your errors:

1) I experienced a number of doubly-recorded counts while wheeling the bike up a long staircase. I also had this happen while dismounted and rolling over level bumpy ground.[

With the single-magnet method it is fairly easy to avoid spurious impulses by excising care and keeping the eye on the meter as the wheel rolls through zero.


2) My normal constant is around 749.xx revolutions per mile. On several occasions I stopped to record data and document the location, and restarted. Then I found myself wondering “Did I stop at 748.xx or 749.xx? By that time I had rezeroed and restarted and had no way to check.

I am not clear as to why an error should happen here, but perhaps total rev should be used instead of rezeroing.

3) I have found it necessary to think carefully when I land on a point and the reading is near zero on the rim. Is the reading 254.01 or is it 255.01? It depends on whether the magnet has passed the sensor.

The sensor can be easily adjusted so that the meter increments within 0.01 of the zero point on the rim, but this is not necessary. The measurer should stop within a rev of the goal or mark. Say the meter reads 123 here. The wheel should then be rolled forward through the zero point. If the goal or mark is at 0.99 on the rim, then the total reading should be recorded as 123.99 irrespective of any later readings of the meter. Similarly if the rim reading is 0.01, total reading is recorded as 124.01.
Alternatively, readings could be taken outside the region within 0.05 of zero with negligible error.

4) The Protégé went into sleep mode while I was documenting a point. I could not remember whether I was supposed to reset it or just roll on. I now know what to do, but at the time I was confused.

Actually the computer has just to be awakened not reset before resuming the ride. A memory aid would be that if this was not necessary then no mention would have been made of it.
 
Posts: 304 | Registered: 01 November 2004Reply With QuoteReport This Post
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