Until January 2003, the Food Safety and Inspection Service (FSIS) tested for the presence of Escherichia coli O157:H7 in raw ground beef and beef trim using an approach in which all beefproducing establishments were sampled at approximately the same frequency. Because all eligible establishments had an equal probability of being selected for verification sampling, FSIS resources were allocated uniformly among establishments that may differ greatly in terms of their microbiological controls for E. coli O157:H7 in ground beef and trim, and the resulting public health impact of these products.

As part of its effort to provide improved public health assurance of the safety of ground beef, FSIS developed an E. coli O157:H7 risk-based verification sampling program. This algorithm was independently peer reviewed in accordance with the Office of Management and Budget guidelines for peer review.

The risk-based E. coli O157:H7 sampling program provides more comprehensive verification of domestic ground beef servings and allocates more samples to establishments with a higher risk of causing E. coli O157:H7 illness. The risk-based sampling algorithm allocates samples in a random draw where the probability of each establishment being sampled is weighted by FSIS microbiological test results for E. coli O157:H7 and production volume. As FSIS collects and analyzes data on establishment E. coli O157:H7 interventions and testing programs these will also be used to weight sampling probability. In the simplest terms, the greater an establishment’s potential for causing E. coli O157:H7 illness, the higher the probability it will be sampled.