I must agree with Mark. When I did the work it was very hot on the road, and I sweated like a horse doing the solo taping. On the biking, I was not used to the calibration course. I generally do better riding on a familiar calibration course than on one which I have never ridden before.
One of these mornings, when it is cool, I will go out and do four rides each way, yielding four uphills, four downhills, and eight flats. Perhaps the data will be slightly better. Perhaps not. I have to use the tools I've got, which include my riding capabilities.
Now - how to assure that the calibration courses are the same length? I have no intention of remeasuring them.