Table 2. Linear regression model for orang-utan abundance on an expedition, conditional on at least one detection.
Estimate | Std. Error | z value | Pr(>|z|) | |
Intercept Model 2a | 21.500714 | 5.689382 | 3.779 | 0.000527 *** |
Intercept Model 2b | 21.487783 | 5.685365 | 3.779 | 0.000513 *** |
Year Model 2a | −0.011465 | 0.002917 | −3.931 | 0.000337 *** |
Year Model 2b | −0.011317 | 0.002911 | −3.888 | 0.000372 *** |
Person Model 2a | 0.028371 | 0.029204 | 0.971 | 0.337299 |
log(Days) Model 2a | 0.708796 | 0.108887 | 6.509 | 1.02e-07 *** |
log(Days) Model 2b | 0.677241 | 0.103856 | 6.521 | 8.76e-08 *** |
Model 2a provides full model of non-zero abundance. Model 2b provides model of non-zero abundance, omitting Person. Year = year in which expedition was conducted. Person = number of people on an expedition. Log(Days) = natural logarithm of duration of expedition in days. Residual standard error in Model 2a: 0.97 on 39 degrees of freedom. Residual standard error in Model 2b: 0.9693 on 40 degrees of freedom. Significance code: ‘***’: p<0.001.