Donkeys in Kenya. Tricky to find the weight of a donkey in the “field” – no pun intended! So using a few measurements, estimate the weight. Other covariates include age. Standard practice is to fit:
for adult donkeys, and other slightly different models for young/old and ill donkeys. What can a statistician add:
- Add in other factors;
- Don’t (automatically) take logs of everything;
- Fit interactions.
Digression on nomograms
- curved scaled nomograms;
- some others that I missed.
Back to donkeys
If we used a log transformation for weight rather than square root we get slightly higher weights for smaller/larger donkeys. Nomograms nicely highlight this.
Nomograms can be clearer and simpler, but don’t display predictive uncertainty.