Verifying complexity empirically



Hi
What would be the best way to verify complexity of an algorithm
empirically ?
Specifically we have ( n1 , t1) , (n2, t2) , ..... ( nx , tx) what
represent input size and average execution time for the algorithm. and
I want to verify that this algorithm is O(n*log n) but neither O(n)
nor (n^2).

.