Motec Varience Doesn't Match Lap Time Difference

To All,

As the title says I review two (2) laps from the same session and the Variance (F3) does not match the indicated lap time differences. I have attached an interpreter screenshot with two (2) selected laps as an example. The actual laptime difference between laps 3 and 4 is 0.571 secs whereas the variance shows 0.529 secs. I have attached the motec datafile and interpreter screenshot (I could not upload the motec C185 configuration file). The differences can be far worse than this.

Any insight is appreciated.

I'm betting on lap distance related issues. This will always make it hard. The use of the variance isn't the final lap time difference, since you already know that. The idea is to show you where the difference comes from, so places where it slopes up and down are the interesting track sections for analysis.

A quick look at your screenshot tells me T1(traffic?), and T5 is where you lost most of the .5 sec!

If you have a smooth straight line that goes from 0 to 0.52 Then I can see how you might care about a couple of tenths.

Hi Brian,

Can you check the settings that you have for Distance Stretching. (Tools | Corrected Speed and Distance... | Corrected Distance tab) The default value is 5% but your laps slightly exceed this. If this value is changed to 6% (I have mine at 10%) then the variance at the end of the lap matches that of the Data tab.