Thanks @ammie and @Lambrae. Your answers to Q 1,2 and 4 do make sense and align with my interpretations too. Your simple example to explain the concept of the validation rule was great. However, I find this rule could still flew the results in real-life price fluctuations and could void some real re-rates. I did four hypothetical case studies last night to test this rule and I can see some discrepancy in validation. The problem I see is not the concept, but the parameter we used (i.e. 50%). Not a criticism of the previous system at all - do not take it that way please - but I am trying to be more transparent and minimise potential issues upfront. I will first try coding, and hope to run a considerably sized sample to calibrate the parameter in question. As we have only a few tips older than 8 weeks, I think we are not in a big rush to see the jerseys under this leg of the competition. Cheers, CC