Average interval among a series of numbers

[typo]

Anyone knows any formula to obtain average interval among a series of numbers? Statistical, mathematical, etc? Interval between the first number and second, second and third, etc, until the end of the series?

[Troodon]

- iterate from first to second-to-the-last number to calculate absolute values of intervals;
- calculate mean of intervals.

if you don't care about absolute (>= 0) values for the intervals then its simpler:

((a[2] - a[1]) + (a[3] - a[2]) + ... + (a[n] - a[n-1])) / (n - 1) = (a[n] - a[1]) / (n - 1)