Table 6 

Comparison of path models. 

Maximum Likelihood Analyses 

Model 
Path constrained to zero 
χ^{2} 
df 
P 
AIC 
Δ_{i} 
w_{i} 
Evidence Ratio 


1 
Head length → Fitness 
5.38 
7 
0.61 
61.38 
0 
0.28 

2 
Max. swim speed → Fitness 
1.98 
5 
0.85 
61.98 
0.60 
0.21 
1.35 
3 
Head ht. → Fitness 
4.28 
6 
0.64 
62.28 
0.89 
0.18 
1.56 
4 
Tail muscle ht. → Max. swim speed 
8.39 
8 
0.40 
62.39 
1.00 
0.17 
1.65 
5 
Tail fin ht. → Max. swim speed 
1.58 
4 
0.81 
63.58 
2.19 
0.09 
3.00 
6 
Tail length → Max. swim speed 
1.20 
3 
0.75 
65.20 
3.81 
0.04 
6.73 
7 
Tail muscle ht. → Fitness 
0.89 
2 
0.64 
66.89 
5.51 
0.02 
15.70 
8 
Head ht. → Max. swim speed 
0.36 
1 
0.55 
68.36 
6.98 
0.01 
32.77 
9 
Saturated model 
 
0 
 
70.00 
8.62 
0.00 
74.33 


Chisquare values (χ^{2}), degrees of freedom (df), and the associated P value report the significance of the model. Note that model 9 is saturated, and thus the fit of the model to the data could not be tested using the chisquare statistic. In models that are not significant, the data are a good fit to the model. AIC = Akaike Information Criterion; Δ_{I }= difference in AIC scores between the best model and subsequent model; w_{i }= normalized relative likelihood of the model given the data; Evidence Ratio = the relative odds that a model is the best given the data. 

Calsbeek and Kuchta BMC Evolutionary Biology 2011 11:353 doi:10.1186/1471214811353 