title: What is the importance of average in performance metrics?
body: <p>As part of the performance tuning and load tests we usually do, i am forced to believe that we need to look at 90th percentiles. As per my understanding 90 times out of hundred people got a respone which is equal to or better than the 90th percentile number. However my current clients always look at average number.What is the impact of only looking at average? Most of the times, I see that between two tests, if average is lower in test A , then 90th percentile is also less in test A.</p>
  
  <p>So should we match the SLA on average or on 90th percentile? </p>