when correlation required

Two ways: First we can scan for correlations,
and see the list of values, which can be correlated.
From this we can pick a value to be correlated.
Secondly, we can record two scripts and
compare them. We can look up the difference
file to see for the values, which needed
to be correlated.  In my project, 
there was a unique id developed for each customer, 
it was nothing but Insurance Number,
it was generated automatically and it was
sequential and this value was unique.
I had to correlate this value, in order
to avoid errors while running my script. 
I did using scan for correlation.