▁of ▁the ▁total ▁re venue ▁function ▁that , ▁for ▁the ▁specific ▁allocation , ▁yields ▁a ▁re venue ▁higher ▁than ▁the ▁wind fall ▁re venue . ▁ ▁The ▁opportun eness ▁may ▁be ▁considered ▁as ▁the ▁imm unity ▁to ▁wind fall ▁success . ▁Therefore , ▁lower ▁opportun eness ▁is ▁preferred ▁to ▁higher ▁opportun eness . ▁ ▁If , ▁for ▁some ▁allocation ▁, ▁we ▁will ▁illustrate ▁the ▁correlation ▁between ▁the ▁wind fall ▁re venue ▁and ▁the ▁robust ness , ▁we ▁will ▁have ▁a ▁graph ▁somewhat ▁similar ▁to ▁Figure ▁ 1 0 . ▁This ▁graph , ▁called ▁opportun eness ▁curve ▁of ▁allocation ▁, ▁has ▁two ▁important ▁features , ▁that ▁are ▁common ▁to ▁( most ) ▁opportun eness ▁curves : ▁▁ ▁The ▁curve ▁is ▁non - de cre asing . ▁This ▁capt ures ▁the ▁notion ▁that ▁when ▁we ▁have ▁higher ▁requirements ▁( high er ▁wind fall ▁re venue ), ▁we ▁are ▁more ▁imm une ▁to ▁failure ▁( high er ▁opportun eness , ▁which ▁is ▁less ▁des irable ). ▁That ▁is , ▁we ▁need ▁a ▁more ▁substantial ▁deviation ▁from ▁the ▁estimate ▁in ▁order ▁to ▁achieve ▁our ▁am bit ious ▁goal . ▁This ▁is ▁the ▁trade off ▁between ▁quality ▁and ▁opportun eness . ▁ ▁At ▁the ▁nom inal ▁re venue , ▁that ▁is , ▁when ▁the ▁critical ▁re venue ▁equals ▁the ▁re venue ▁under ▁the ▁nom inal ▁model ▁( our ▁estimate ▁of ▁the ▁re venue ▁functions ), ▁the ▁opportun eness ▁is ▁zero . ▁This ▁is ▁since ▁no ▁deviation ▁from ▁the ▁estimate ▁is ▁needed ▁in ▁order ▁to ▁achieve ▁the ▁wind fall