Consider these:Hours worked per week ___ vs. ___ Productivity per week
(ex. product quality, site speed, user growth)Click through rates ___ vs. ___ Long click through rates
Average response time ___ vs. ___ 95th or 99th percentile response times
Registered users ___ vs. ___ Weekly growth rate of registerd users
Weekly active users ___ vs. ___ Weekly active rate by age of cohour
(Measure the fraction of users who are still weekly actives the nth week after signing up, and track how that number changes over time