How are the periods preceding and following a challenge defined?

To assess the evolution of driving behavior, it is interesting to compare the average score of a driver during the challenge with the one measured during the period preceding the challenge. The average score before the challenge is calculated over a period of 14 days preceding the date of the start of the challenge minus 10 days.

To know if a driver maintains his efforts after a challenge, it is also interesting to compare his average score during the challenge with the one measured in the period following the challenge. The average score after the challenge is calculated over a period of 14 days following the end date of the challenge plus 10 days.