Whether a filer's side actually won — measured against what the
same positions would have produced by chance.
Only three states record which side a lobbyist took on a bill, and two of
them have bill outcomes we can match: Colorado and Iowa. Nebraska records
positions but its data may not be sold, so it is not scored here.
This is a record, not a measure of influence. Lobbyists choose winnable fights and already-sympathetic legislators, most lobbying never appears in any filing, and a contested bill has filers on both sides with no way to apportion credit between them. What is measured here is the alignment between a position someone declared and what then happened to the bill.
Why not a win rate
Because a win rate mostly measures which state someone works in. Colorado
passes about three quarters of the bills anyone bothers to lobby; Iowa kills
about three quarters. Support everything in Colorado, or oppose everything in
Iowa, and you "win" three times in four without doing anything at all. The only
number worth publishing is the difference from that baseline.