5 / 9 Requirements & Scoping

What Fast Actually Means

The product owner writes the requirement as "checkout should feel fast." You have to turn that into one number a dashboard can compute every minute. Four teams propose four measurements. Which one is closest to the stated requirement?

A

p99 measured at the load balancer, with 5xx responses excluded from the sample

B

p99 of the checkout handler's own execution time, measured inside the application process

C

p99 of the time from the user's tap to the confirmation screen being painted, reported by the mobile client over every session that entered checkout

D

Mean end-to-end checkout duration across all users