Average Response Time is calculated as an average of durations of the web transactions simulated on the target website at a given time interval:
Av.Response Time = ∑ time of transaction duration / the number of transactions started
Where a transaction is a sequence of completed operations performed on a web resource by a visitor or a sequence of HTTP(S) requests and replies. Time of transaction duration is a time elapsed from the moment the transaction is started at to the moment it is completed. As an example of a transaction we can consider a sequence of such operations as loading a web page, logging in to the site, navigating to another page and submitting a web form.
A transaction duration time DO NOT include a browser launch and shutdown time.