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Table 5 Factors influencing (a) action production, (b) tactile gesture production, (c) visual gesture production and (d) initiator of carry initiation in mother–infant dyad

From: Should I stay or should I go? Initiation of joint travel in mother–infant dyads of two chimpanzee communities in the wild

  Estimate se χ 2 P LRT χ 2 df P
(a) Action
Intercept −0.758 0.318 (a) (a) 23.476 7 0.001
Role (mother) 0.217 0.207 (a) (a)    
Within-infants age −0.185 0.201 (a) (a)    
Between-infants age −0.988 0.248 (a) (a)    
Carry necessity 0.009 0.154 0.003 0.953    
Parity 0.007 0.096 0.005 0.942    
Party (females) −0.042 0.24 0.031 0.861    
Party (mixed) −0.127 0.237 0.287 0.592    
Infant sex (male) 0.019 0.185 0.010 0.919    
Site (Taï) 0.407 0.195 3.705 0.054    
Role: within-infants age 0.215 0.223 0.924 0.336    
Role: between-infants age 0.756 0.25 11.668 0.001    
(b) Tactile gesture
Intercept −1.437 0.383 (a) (a) 18.968 7 0.008
Role (mother) 0.065 0.258 0.064 0.800    
Within-infants age −0.164 0.089 2.824 0.093    
Between-infants age 0.049 0.136 0.139 0.709    
Carry necessity 0.649 0.210 9.861 0.002    
Parity −0.019 0.11 0.030 0.863    
Party (females) 0.274 0.331 0.683 0.409    
Party (mixed) 0.149 0.299 0.253 0.615    
Infant sex (male) 0.006 0.218 0.001 0.979    
Site (Taï) 0.646 0.233 5.479 0.019    
(c) Visual gesture
Intercept −3.134 0.428 (a) (a) 52.795 7 <0.001
Role (mother) 2.380 0.359 46.963 <0.001    
Within-infants age −0.006 0.106 0.003 0.957    
Between-infants age 0.182 0.090 2.973 0.085    
Carry necessity 0.436 0.163 5.785 0.016    
Parity 0.109 0.082 1.760 0.185    
Party (females) −0.148 0.252 0.343 0.558    
Party (mixed) 0.122 0.245 0.250 0.617    
Infant sex (male) −0.069 0.16 0.187 0.665    
Site (Taï) 0.029 0.168 0.029 0.864    
(d) Infant carry initiation
Intercept −1.944 0.476 (a) (a) 24.320 4 <0.001
Within-infants age 0.547 0.242 3.297 0.069    
Between-infants age 0.779 0.163 16.235 <0.001    
Carry necessity 0.004 0.286 0.000 0.990    
Parity 0.651 0.148 11.601 0.001    
Party (females) 0.912 0.482 3.836 0.050    
Party (mixed) 0.768 0.470 2.807 0.094    
Infant sex (male) 0.027 0.297 0.008 0.928    
Site (Taï) 0.468 0.286 1.923 0.165    
  1. Bold values indicate P < 0.05
  2. (a)Significance test not indicated because it has no meaningful interpretation