One serves a mostly rural clientele, the other also serves pockets of population. The study attempted to quantify benefits to non-users of public transit as well as users to portray total benefits. Some are willing to pay for it even if they don't use it, because it gives them the option of using it or because they feel it is a quality of life improvement for deserving citizens. Businesses are non-users but their customers and clients may use it so they benefit as well. The technique has been used to measure non-user economic values for environmental amenities.
Contingent valuation uses responses from interviewees to quantify their estimates of benefit.
Questions are posed in different ways to get them to identify a value. The lower figure aggregates responses by household. The upper figure aggregates by population age 20 and older. True aggregate benefit probably lies somewhere in between, the economists say. The figure lies midway in the range of benefits.