Vendor Evaluation Scoring methods E & F

Dear Folks,

In the vendor evaluation, I see two scoring methods:

E Determination of Price Variance from Invoice Documents

F Determination of Quantity Variance from Invoice Documents

Can anyone advice me how these two scoring methods works?

For example, the method E, price variance from invoice documents. What does it means? It's the price variance from invoice documents against what? Is it against the PO price?

And for method F, what's the quantity variance compared against? GR quantity or PO quantity?

Best Regards

Junwen