A well-proven methodology (the modified Delphi method) was used to generate a first-order approximation of errors that should be measured in a virtual reality surgical simulator (the ES3). The methodology and the errors derived were crafted in such a way as to be generalizable. Although some of the error measures are specific for sinus surgery, the same type of methodology can be used for other otolaryngologic, general, and [table: see text] subspecialty surgical procedures. The value of this process is that it can provide a uniform framework for investigators in surgical education and training to establish error measurements in their particular procedures or disciplines and to generate data and outcomes that are comparable, interoperable, and sharable with other investigators. Admittedly, the process is time consuming and rigorous, but it does provide a solid scientific basis to generate evidence-based data for the validation of training methods and for outcomes analysis.