The investigators present an operator method for obtaining upper and lower bounds for the expected length of a collision resolution interval for various protocols. The method is elementary in that it circumvents the intricate and ingenious complex variable methods of Fayolle, Flajolet and Hofri (1983). It is also noted that the method can be applied to computing upper and lower bounds for the conditional delay. The problem of computing upper and lower bounds for the variances by this method remains open. (Author)