How can i get first response time & number of responses from API?

How can i get first response time & number of responses from API?

I try to fetch this details on each ticket but the 
data that come from your API isnt good, my API request is:
'https://desk.zoho.com/api/v1/tickets/'. $id .'/metrics'

then i get several fields like: responseCount, threadCount and more.
But when i compare those fields with my tickets  i cant find out what is the right field.

Any help?
And is there a way to fetch several tickets with this info? 
with this request :https://desk.zoho.com/api/v1/tickets/search?...
I cant get this fields...