Accuracy is established after the estimate has been completed and a Monte Carlo risk analysis has been performed. If, however, we focus on quality first, improved accuracy should naturally follow.The recommended industry standard within the oil, gas and chemical industry was established by the AACE International Recommended Practice 18R-97. This practice establishes usage, preparation methodology and accuracy as the classes of estimate and which class is appropriate for a given phase of a project. Having this industry standard is all well and good, but it doesn’t address quality. So, what can we as estimating professionals do to improve the quality of the various classes of estimates?Improving the quality of estimates starts with improving everything that directly affects them: well-trained estimators, adherence to standard operating procedures and best practices, inputs, execution strategies, project schedules, unit costs and identified project risks.