To estimate the range of direct benefits provided to users from public library services, the SLPL researchers selected these methodologies. Consumer surplus was the first measurement selected.
Consumer surplus is used frequently by economists in policy studies.
Consumer surplus measures the value that consumers place on the consumption of a good or service in excess of what they must pay to get it. This time and effort represent an implicit price to the patron. Moreover, many alternatives to library services are sold in the marketplace. For example, households can buy novels rather than check out the library's fiction books. In a telephone survey, interviewers asked patrons about the number of books they borrow from the library, the books they purchased, and additional books that they would buy if they could not borrow.