Table 3.
Median with interquartile range (IQR), maximum number of holdings and probability of detection for the different combinations of classical scrapie (CS) and atypical scrapie (AS) cases using the simulation of actual Fallen stock survey data and randomly extracted data from the census for three 4-year periods
| Actual | Random | |||||
|---|---|---|---|---|---|---|
| No. of holdings with cases | Detection probability | Median no. holdings (IQR) | Maximum no. holdings | Detection probability | Median no. holdings (IQR) | Maximum no. holdings |
| 2006–2009 | ||||||
| 1 AS case | 1 | 72 (79–67) | 104 | 1 | 76 (82–70) | 123 |
| 2 AS cases | 0·83 | 2 (3–1) | 9 | 0·15 | 0 (0–0) | 5 |
| 3 AS cases | 0·08 | 0 (0–0) | 3 | 0·0001 | 0 (0–0) | 1 |
| ⩾1 AS case, 1 CS case | 0·99 | 6 (8–5) | 18 | 0·55 | 1 (1–0) | 8 |
| ⩾1 AS case, 2 CS cases | 0·4 | 0 (1–0) | 7 | 0·0009 | 0 (0–0) | 2 |
| ⩾1 AS case, 3 CS cases | 0·06 | 0 (0–0) | 2 | 0·00004 | 0 (0–0) | 1 |
| 2007–2010 | ||||||
| 1 AS case | 1 | 61 (66–55) | 88 | 1 | 64 (69–58) | 94 |
| 2 AS cases | 0·81 | 1 (2–1) | 8 | 0·11 | 0 (0–0) | 3 |
| 3 AS cases | 0·08 | 0 (0–0) | 3 | 0·0004 | 0 (0–0) | 1 |
| ⩾1 AS case, 1 CS case | 0·99 | 6 (8–4) | 17 | 0·44 | 0 (1–0) | 8 |
| ⩾1 AS case, 2 CS cases | 0·38 | 0 (1–0) | 5 | 0·003 | 0 (0–0) | 1 |
| ⩾1 AS case, 3 CS cases | 0·05 | 0 (0–0) | 2 | 0 | 0 (0–0) | 0 |
| 2008–2011 | ||||||
| 1 AS case | 1 | 59 (65–54) | 123 | 1 | 64 (69–58) | 93 |
| 2 AS cases | 0·68 | 1 (2–0) | 7 | 0·11 | 0 (0–0) | 3 |
| 3 AS cases | 0·04 | 0 (0–0) | 4 | 0·004 | 0 (0–0) | 1 |
| ⩾1 AS case, 1 CS case | 0·98 | 4 (6–3) | 14 | 0·47 | 0 (1–0) | 5 |
| ⩾1 AS case, 2 CS cases | 0·26 | 0 (1–0) | 4 | 0·0006 | 0 (0–0) | 1 |
| ⩾1 AS case, 3 CS cases | 0·03 | 0 (0–0) | 2 | 0 | 0 (0–0) | 0 |