The goal of a special interest group is to pull policy in their preferred direction. The distinction between mean and median preferences suggests the possibility that this is actually efficient, though few observers see it that way. If interest groups disagree, moreover, they may directly cancel each other out. More money for schools means less for the environment, or defense, or something else. The most popular answer is campaign contributions .
Special interests move policy away from voter preferences by making donations to politicians.
B. Cash donations are everyone's favorite example, but in-kind contributions of labor, printing, and so on are also important. Political advertising is the standard example here. The usual answer appeals to voters' rational ignorance. The ads are aimed at uninformed voters who are easy to sway. F. Compare this to buying a used car.