How to find the type of association between the attributes when N = 126; (A) = 90, (B) = 56 and (AB) = 40.
Step 1: Using comparison method we note (AB) = 40.
Step 2: [(A) x (B)] / N = [90 x 56] / 126 = 40.
Since (AB) = [(A) x (B)] / N, we can say the attributes are independent.
Two attributes are said to be independent if there does not exist any kind of relation between them. Using Comparison Method -
Attributes are independent when (AB) = (A) x (B) / N
Attributes are positively associated when (AB) > (A) x (B) / N
Attributes are negatively associated when (AB) < (A) x (B) / N