Factor, parameter or model feature affected by the uncertainty	One sentence description of the cause of uncertainty affecting this factor, parameter or model feature (one row per cause of uncertainty)	One sentence description of how this source of uncertainty might lead to incorrect answer, or why that might be possible
Structural integrity of the brain/brainstem at the time of sampling	The analytical sensitivity and specificity of PrPSc detection methods are unaffected by autolysis, but if structural integrity is lost due to autolysis following delayed sampling, it may not be possible to take the correct anatomical areas, or to ensure that the correct areas have been included in the sample. False negatives may occur if the wrong area is sampled. An inaccurately sampled positive case may have insufficient anatomically correct tissue to enable the confirmatory diagnostic step to be performed	It is almost certain that autolysis would be limited in the controlled environment of chilled storage for 24 or 72 h after slaughter and would not exceed the tolerance already in place for fallen stock