how would you measure the loyalty of a person?

if amidst your insensitivity he/she chose to be with you often.

yes you can measure the loyality of a person such as if u send him around k city h came again to you this is the shortest work to measure the loyality of a person Hope u understand my opinion Bye Have a nice day

if he never leave you in good times and bad.

For me, as long as this person showing me his/her love for me. As long as he or she still accepts my flaws, he/she doesn't tolerate wrong things i've done. As long as he/she makes me feel that i am still important in their life.....

Yes you can measure it when you are in trouble.

Well, there are ways, but you didn't specify if of a friend, gf/bf, a relative, etc. The best way is by personal experience if you've interacted with that individual at all. The other way is if you don't know them, perhaps some one that you know- really does and can give you the skinny on them. The measure you'd use, of course, would be directly effected by the disloyalty this individual has shown in the past.