Race Time Difference Charts - How are they done?

[tok-tokkie]

Here is the time difference chart for the Bahrain GP:


Chart from James Allen

1. It shows Vettel with a time difference of over 40 seconds after the second pit stop. 40 seconds behind what? (Compared to his race average lap time?)
2.What happens to HRT & Marusia after the second pit stops? They really fall way behind the others. It looks like their lap times just do not inprove as the fuel load burns off - is that correct?
3. I was really surprised by the difference in the graphs. It seems to show that Caterham is almost part of the mid field (+1 lap like 1 Toro Rosso) - I had not appreciated they had distanced themselves as much as that from the Cosworth cars.

[Websta]

HRT and Marussia lose a lot of time due to cars lapping them, and as the field gets more and more spread out (as the race progresses), they lose more time as they get lapped more often. That's one possible reason for their relative pace decrease as the race progresses.

[Timbit]

The graphs compare the average total time (average lap time x lap number) on any given lap to the total time on the same lap. The graph is real nifty and I love em to bits (as much as a man can love a time-based graph).

This of course means that the winner will always reach 0 at the last lap on the graph, as the average total time has equaled the winner's total time (that the average total time is based).

These graphs are one of the best ways to compare each driver, where they won and lost time, and where each driver was relative to each other. I find it better through to compare drivers to the race pace of the leader as it better shows the gap between drivers, but that's my own preference.

F1Fanatic does some nice ones, colour coded to match the teams and you can pick and chose which drivers you want to see: http://www.f1fanatic.co.uk/2012/04/22/2 ... lap-chart/