"Failure mode and effect analysis (FMEA) is a common approach to prospectively determine error risk within a particular process. FMEA begins by identifying all the steps that must be taken for a given process to occur ("process mapping") and then how each step can go wrong (i.e., failure modes), the probability that each error will be detected before causing harm, and the impact of the error if it actually occurs. The estimated likelihood of a particular process failure, the chance of detecting such failure, and its impact are combined numerically to produce a criticality index, which provides a rough estimate of the magnitude of hazard posed by each step in a high-risk process. Steps ranked at the top (those with the highest criticality indices) should be prioritized for error proofing."
Read more on "FMEA" and detection of safety hazards on AHRQ's Patient Safety Network site.