Table 1.
Results from a general linear model constructed to analyse the variation in the magnitude of the IFN-γ response at the disclosing test (recorded as both PPD-B minus negative control and PPD-B minus PPD-A), in relation to the following explanatory variables: outcome infection status, age, sex and source population, for 56 badgers captured in Gloucestershire between 2006 and 2012
| Response variable | Explanatory variables | Level | Estimate1 (SE) | t(50)2 | P value |
|---|---|---|---|---|---|
| PPD-B minus negative control | Outcome infection status (reference level IFN-γ positive only) | Stat-Pak positive | 0·53 (0·19) | 2·77 | 0·008 |
| Culture positive | 0·96 (0·29) | 3·37 | 0·001 | ||
| Age (reference level adult) | Cub | −0·64 (0·19) | −3·30 | 0·002 | |
| Sex (reference level female) | Male | −0·42 (0·16) | −2·61 | 0·012 | |
| Source population (reference level BVS) | WP | 0·13 (0·22) | 0·58 | 0·566 | |
| PPD-B minus PPD-A (B–A) | Outcome infection status (reference level IFN-γ positive only) | Stat-Pak positive | 0·54 (0·19) | 2·86 | 0·007 |
| Culture positive | 1·01 (0·28) | 3·55 | < 0·001 | ||
| Age (reference level adult) | Cub | −0·59 (0·19) | −3·03 | 0·004 | |
| Sex (reference level female) | Male | −0·38 (0·16) | −2·40 | 0·020 | |
| Source population (reference level BVS) | WP | 0·23 (0·22) | 1·06 | 0·297 |
Estimate from the model of the difference in the mean value relative to the reference level, with its associated standard error (SE).
The test statistic from the model output with associated degrees of freedom in brackets.
Note: Significant effects are shown in bold, P < 0·05.
Abbreviations: BVS, Badger Vaccine Study; IFN-γ interferon-γ; PPD-A, purified protein derivative from Mycobacterium avium; PPD-B, purified protein derivative from Mycobacterium bovis.