<div class="htmlview paragraph"><i>A number of simplistic formulae, based on particle dynamics, energy, and momentum methods are routinely employed by accident reconstructionists to calculate vehicle speeds immediately prior to impact. It is almost always the case that scene evidence and other information regarding important variables involved in such equations must either be estimated or can be measured only in an approximate way</i>.</div> <div class="htmlview paragraph"><i>In the present work, we examine the sensitivity of such standard calculations to variations in the measured or estimated values of the independent variables needed for calculation. The traditional methods of the calculus are employed. Example problems illustrate the difficulties faced by accident reconstructionists as they grapple with incomplete and/or estimated values for important variables, and with the inherent sensitivity of some of the calculations to seemingly small variations in variable magnitudes</i>.</div>