Take two numeric vectors and return the Akaike Information
Criterion (AICc) corrected for the second order.
AICc is computed from the Residuals Sum of Square
(rss) and
the number of used parameters.
AICc(x, y, nbK)two numeric vectors of same length.
an integer. nbK is the number of used parameters.
nbK > 1 : returns NA if not.
Return the Akaike Information Criterion ((AICc)),
corrected for the second order bias.
The correction for the second order bias
improves the Akaike Information Criterion
when (length(x)) is small.