An airport expansion is implemented during a period of positive global economic prospects and expected increase in the demand of air traffic, and ex-post evaluated just after the Covid-19 pandemic. How would you expect the value of the SDR adopted for the ex-post CBA, both backward and forward, to be in respect of the one adopted in the ex-ante CBA, the rest being equal? How would you mitigate the possible bias in the ex-post CBA related to its timing in the economic cycle?