Table 3 Best-fit general linear mixed-effect (GLMM) models showing the relationship between ‘true’ and IRT-derived RR and HR values with species ID as a random effect to account for any species where multiple individuals were imaged. Fixed effects were added to investigate the role of physical characteristics in IRT-EVM errors. Models are ordered by AICc, with best models at the top of the table; the base model is included. See Additional file 1, Table S1 for additional model information
RR models | ||
 Base model: true RR x IRT RR + species ID (random effect) | ||
Added fixed effect | AICc | R2 adjusted |
 Thickness of integument | 183.17 | 0.9836 |
 Base model | 185.41 | 0.9647 |
 Immobilized or voluntary | 186.47 | 0.9663 |
 Taxa | 189.32 | 0.9664 |
 Significant presence of subcutaneous fat | 187.95 | 0.9649 |
 Integument | 192.40 | 0.96640 |
HR models | ||
 Base model: true HR x IRT HR + species ID (random effect) | ||
Added fixed effect | AICc | R2 adjusted |
 Taxa | 175.87 | 0.9573 |
 Integument | 179.48 | 0.9573 |
 Base model | 185.00 | 0.9284 |
 Thickness of integument | 187.67 | 0.9300 |
 Significant presence of subcutaneous fat | 187.84 | 0.9295 |
 Immobilized or voluntary | 188.13 | 0.9287 |