An RFP to 20 law firms sounds great – “proposals from that many will give us more insights, more leverage, stronger competition, and a better selection” – but the selection team has almost certainly overestimated its capacity tor manage all of the choices it needs to make(See my post of Nov. 13, 2006: decision difficulties when there are too many choices.). An article in strategy+bus., Winter 2010 at 65, offers a more precise critique. “Psychological studies have consistently shown that it’s very difficult to compare and contrast the attributes of more than about seven different things.”
The point is, if you compare 20 law firms on multiple attributes, including costs, expertise, bench, number of lawyers, diversity efforts, commitment to pro bono, and technology, your team will likely flounder, feel overwhelmed, and punt. The default choice that alleviates the overload of choices, the most familiar law firm or the name brand firm, will probably be selected.
All is not lost. Among the strategies available to cope with combinatorial overload, you can make a first cut based on a handful of most important criteria, you can winnow the number of firms that make it to the final round, you can allocate parts of the rating system to different members, or you can use various decision analysis tools to do some of the heavy lifting.