And Random Index, or R.I. is the consistency index of
a pairwise comparison matrix which is generated randomly.
Random index depends on the number of elements which are
compared and as it is shown in Table II; in each case for
every n, the final R.I. is the average of a large numbers of
R.I. calculated for a randomly generated matrix.
The final consistency ratio C.R. is calculated by comparing
the C.I. with the R.I.. And if C.R < 0.1, then the consistency
is acceptable, otherwise the comparison matrix should be
modified and all calculation should be performed again, until
the consistency ration meet the need.