how would you measure quality of life for cats and their food?
Already answered, Here and Here
If you are asking for an example of a specific methodology, I’ve no idea, I’m neither an animal behaviour nor nutrition researcher.
In the same way i wouldn’t be able to provide a specific methodology for measuring orbital decay or the long term effects of language drift on emotional responses, because I’m not a physicist , linguist or psychologist either.
That’s one of the reasons for peer reviewed research by specialists.
Sure
if it ticks the two boxes then it’ll be useful to know :
1 : [ ] Independent
2 : [ ] Has provided long term, reproducible, studies with reasonable sample sizes and empirical data based results.