ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

[tigerluver]

@peter, thank you for sharing that table. It gives us a dataset to create a predictive regression equation.

I split the dataset into two. The first set of graphs does not use the same individual multiple times if multiple measurements were available. Rather, each individual is represented just once with greatest pad width (and the corresponding weight at that measurement).

*This image is copyright of its original author

This next set of graphs utilized all measurements on that table such that if an individual is measured multiple times it is represented multiple times. This could be a reasonable approach as well as it still shows weight change with pad growth and is based on a greater sample size of measurements.

*This image is copyright of its original author

When pooling together males and females, the fit is mediocre however there is a significant relationship. When we split the sexes, we note that males seem to have a very strong and significant association between pad size and mass in both models (R^2 >=0.9). On the other hand, females have a poor association. What could be the reasoning for such? Perhaps the females were not in equal shape between specimens, some emaciated while others not. It is also possible the measurements weren't done as precisely. 

Using all tigers and not allowing one individual to be represented multiple times temporally, a 13.5 cm pad would weigh 226 kg. Using all tigers but allowing an individual's multiple measurements to be included in the foundation, the estimate would be 221 kg. 

Using only males and not allowing one individual to be represented multiple times temporally, a 13.5 cm pad would weigh 283 kg. Using only males but allowing an individual's multiple measurements to be included in the foundation, the estimate would be 274 kg. 

The reader can decide which formula they like best. As stated before, the pooled equation has poor r^2 and thus likely a much weaker estimate compared to the only male equations.

For the sake of completeness, I'll add in an isometry estimate. Using the largest pad sizes of the 5 males (average pad size 11.1 cm, average weight 152 kg), the isometric estimate of a 13.5 cm pad would be 275 kg. If we use all temporal measurements and allow specimens to be represented multiple times (average pad size 10.5 cm, average weight 137 kg), the isometric estimate is 291 kg. Reply