This study investigated the use of normative rules by baseball umpires. Normative rules are informal standards of conduct that deviate from the official rules of sport. Sixteen umpires, 25 coaches, and 27 baseball players defined the official upper and lower boundaries of the strike zone, marked these official boundaries on a Strike Zone Form, and marked where they actually call, or believe umpires call, the boundaries. Umpires were significantly more knowledgeable about rules than players were. Umpires reported setting the upper boundary of the strike zone significantly lower (an average of 2.64 inches) than the official rule specifies. Coaches and players reported that umpires lower the boundaries, but players overestimated how much umpires deviate from the rule-book boundaries. Results suggest that umpires consciously violate official rules. The ethical implications of these findings are discussed.
Rainey, David W. and Larsen, Janet D., "Balls, Strikes, and Norms: Rule Violations and Normative Rules Among Baseball Umpires" (1988). Psychology. 2.