4.1 Linear regression in statistics

Photo looking back from the 90 meter mark towards the 60 meter mark. 15 more meters than the prior personal best of 75 meters from LRC to the A building.

To semi-quote Herman Melville via Khan Noonien Singh in Star Trek: Wrath of Khan, the health building sidewalk tasked me and I shall ride it!
 

Zero was at the start of the new sidewalk up by the B building. Measurements were done prior to class and took 35 to 40 minutes to layout. Marks were every three meters out to 60 meters. In retrospect this kept me too busy on the RipStik board. Every four meters appears a better option as this would put a gap between 28 and 32 meters, which is the location of the second and faster of the two corners to cope with.

The first turn is between six and nine meters. Timing and turning 90° on a tighter turn than the turn-in to the A building proved challenging. The RipStik run was done cold. No rehearsal. No practice run. Single attempt. 

30 meters happens here, just around a corner that is tight and at which the RipStik is moving all too quickly. I had to use post grabs to slow down into the corner. Hitting the lap timer while at speed and turning proved as difficult as expected. One could remove the 29 meter and 30 meter marks and buy time to focus on setting up the turn. Perhaps more marks should be skipped, or a four meter interval should be used. But as long as the lap timer is being pressed once per mark passed, errors in timing at earlier marks do not propagate or impact the accuracy of later timing marks. 

This is the location of the 30 meter mark. At this point the focus is balancing off of a fast corner onto a rougher surface.

60 meters is just prior to the parking lot.

The view from 60 meters to 90 meters. More distance is possible, but the slope is uphill out beyond 90 meters. 


Orange data points are timing issues related to grabbing posts to slow down and then missing a chalk mark on the sidewalk, the red data points are the second corner.

In class only the run to 60 meters was graphed. Being 4.1 only the graph was generated. Slope and intercept functions are in section 4.2 of the textbook. No times were taken between 60 meters and 90 meters. This was because the time at 90 meters will be predicted off of the first 60 meters - not only was there no need for interval times out beyond 60 meters, their inclusion would make the 90 meter prediction a little less remarkable. Preliminary calculations suggest the predicted time will be within a half second of the actual arrival time at 90 meters.

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