Comparisons of the electric field strength (log E) where stingrays orient toward and bite at weak electrodes
| Parameter . | Model A . | Model B . |
|---|---|---|
| Intercept | 1.533*** (0.057) | 0.884*** (0.221) |
| Urobatis halleri vs Myliobatis californica | –0.305** (0.079) | –0.190** (0.068) |
| Pteroplatytrygon violacea vs Myliobatis californica | 0.040 (0.093) | 0.088 (0.097) |
| Urobatis halleri vs Pteroplatytrygon violacea | –0.305** (0.079) | –0.190** (0.068) |
| Body size | 0.021 (0.035) | –0.013 (0.030) |
| Initial current | 0.093** (0.029) | |
| Turn direction | –0.106* (0.041) | |
| Electrode number 1 vs 4 | –0.099 (0.059) | |
| Electrode number 2 vs 4 | 0.010 (0.059) | |
| Electrode number 3 vs 4 | 0.013 (0.055) | |
| Gender | 0.119 (0.062) | |
| Variance components | ||
| Level 1, residual | 0.470 (0.020) | 0.466 (0.020) |
| Level 2, intercept | 0.024 (0.011) | 0.010 (0.007) |
| Goodness of fit | ||
| –2 log likelihood | 2439.0 | 2416.0 |
| AIC | 2451.0 | 2440.0 |
| BIC | 2481.3 | 2500.7 |
| Parameter . | Model A . | Model B . |
|---|---|---|
| Intercept | 1.533*** (0.057) | 0.884*** (0.221) |
| Urobatis halleri vs Myliobatis californica | –0.305** (0.079) | –0.190** (0.068) |
| Pteroplatytrygon violacea vs Myliobatis californica | 0.040 (0.093) | 0.088 (0.097) |
| Urobatis halleri vs Pteroplatytrygon violacea | –0.305** (0.079) | –0.190** (0.068) |
| Body size | 0.021 (0.035) | –0.013 (0.030) |
| Initial current | 0.093** (0.029) | |
| Turn direction | –0.106* (0.041) | |
| Electrode number 1 vs 4 | –0.099 (0.059) | |
| Electrode number 2 vs 4 | 0.010 (0.059) | |
| Electrode number 3 vs 4 | 0.013 (0.055) | |
| Gender | 0.119 (0.062) | |
| Variance components | ||
| Level 1, residual | 0.470 (0.020) | 0.466 (0.020) |
| Level 2, intercept | 0.024 (0.011) | 0.010 (0.007) |
| Goodness of fit | ||
| –2 log likelihood | 2439.0 | 2416.0 |
| AIC | 2451.0 | 2440.0 |
| BIC | 2481.3 | 2500.7 |
The multilevel regression Model A is the simplest model comparing the three species whereas Model B includes additional variables. Initial current, turn direction, electrode number and gender have no effect on the differences found between species. The estimate is shown with the s.e.m. in parentheses below(*P<0.05, **P<0.01, ***P<0.001). AIC, Akaike's information criterion; BIC,Schwarz's Bayesian criterion