Table 3. Results from Poisson regressions comparing whether the median age at mortality in the AZA and Japan populations differed based on sex, birth type, and between two time periods in captive chimpanzees.
| Estimate | Std. Error | z value | p value | Estimate | Std. Error | z value | p value | ||
|---|---|---|---|---|---|---|---|---|---|
| AZA | Japan | ||||||||
| (Intercept) | 2.41 | 0.12 | 20.75 | <2E − 16 | (Intercept) | 2.42 | 0.16 | 15.41 | <2E − 16 |
| Sex (male) | −0.08 | 0.15 | −0.53 | 0.5951 | Sex (male) | 0.46 | 0.22 | 2.08 | 0.0388 |
| Period (late) | 0.89 | 0.13 | 6.82 | 9.33E − 11 | Period (late) | 0.68 | 0.18 | 3.83 | 0.0002 |
| Birth type (wild) | 0.87 | 0.13 | 6.50 | 5.52E − 10 | Birth type (wild) | 0.71 | 0.19 | 3.83 | 0.0002 |
| Sex (male) * period (late) | −0.16 | 0.14 | −1.18 | 0.2407 | Sex (male) * period (late) | −0.43 | 0.25 | −1.73 | 0.0863 |
| Period (late) * birth type (wild) | −0.32 | 0.14 | −2.19 | 0.0297 | Sex (male) * birth type (wild) | −0.73 | 0.26 | −2.78 | 0.0061 |
| Sex (male) * birth type (wild) | 0.13 | 0.13 | 0.97 | 0.3319 | Period (late) * birth type (wild) | −0.15 | 0.21 | −0.74 | 0.4631 |
| Null deviance: 2528.3 on 221 degrees of freedom | Sex * birth type * period | 0.69 | 0.31 | 2.24 | 0.0263 | ||||
| Residual deviance: 1255.8 on 215 degrees of freedom | Null deviance: 1203.96 on 168 degrees of freedom | ||||||||
| Dispersion parameter for quasipoisson family taken to be 5.782681 | Residual deviance: 686.09 on 161 degrees of freedom | ||||||||
| Dispersion parameter for quasipoisson family taken to be 4.176631 | |||||||||
Note:
The “early” time period is 1975–2000 for AZA and 1980–2000 for Japan, the “recent” period is 2001–2020 for both. Analyses were performed using only mortalities that occurred on or after the first birthdate. Bolded coefficient estimates highlight the effects that were significant at p < 0.05.