DEA would allow a particular warehouse--let's call it the candidate warehouse--to be compared to a large set of other warehouses. DEA would construct a hypothetical composite warehouse from the input and output data for all other warehouses, and this composite warehouse would be compared to the candidate warehouse. The composite would be constructed in such a way that it produces at least as much output as the candidate warehouse, but uses the minimum possible resources. In this sense, it would be a hypothetical "best practices" warehouse. To work effectively, DEA requires a considerable number of warehouses for comparison; it is recommended that at least three or four times as many warehouses should be in the database as there are individual inputs and outputs in the DEA model. Also, when DEA was first proposed, it required computational analysis that was not widely available. These pragmatic considerations have limited the application of DEA, until now.DEA has been implemented in an internet-based tool, iDEAs-W.