Reading your P&L
What are CM1, CM2 and CM3?
Three contribution margins, each subtracting one kind of cost. CM1 is net revenue minus the goods. CM2 subtracts fulfilment and payment fees. CM3 subtracts marketing.
Reading them together tells you which lever moved: if CM1 holds and CM2 falls, the problem is shipping, returns or basket size rather than pricing. The whole ladder, with the decision each margin drives, is in CM1, CM2 and CM3 explained.
Did this answer it? If not, a person who knows the product will.