Table 1.

Overview of tests assessing differences in sociality across four neighboring chimpanzee populations, while statistically controlling for influential behavioral determinants using GLMMs

Measure	Test variable	What it means	Population differences?	What we can infer
Party size	Number of group members near focal subject	Size of social congregations individuals spend time in	P < 0.0001	Population-specific preferences for individuals’ tendency to group together (within eye sight)
Association index	Probability to be in proximity to others	Having established a 1-m association with partners (yes/no)	P < 0.0001	Populations differ due to differences in population size*
Association index	Extent of being in proximity to others	Time spent within 1-m distance of associated partners	P < 0.0001	Population-specific preferences in magnitude by which individuals seek close proximity to others
Association index	Probability to groom others	Having established a grooming association with partners (yes/no)	P < 0.0001	Populations differ due to differences in population size*
Association index	Extent of grooming others	Time spent engaged in grooming with associated partners	P < 0.0002	Population-specific preferences in magnitude by which individuals engage in grooming with others

^*After controlling for population size, the P values for population identity were 0.98 and 0.71, respectively (Results). All P values are Bonferroni–Holm-corrected.