The extra cost of warehousing averaged 8.9 per cent of the ongoing cost in case companies, but there was large variation. For four products (A, B1, B3 and F) the percentage turned out to be high, representing from 13-18.8 per cent of the ongoing cost, for others it was much lower. This cost was only mentioned by one of the survey companies, who estimated it at 3.8 per cent. This was the largest of the non-price cost differences between the case and survey companies and may suggest underestimation of total ongoing cost by the surveyed companies.