Apdex Index Examined

This month's edition of the CMG MeasureIT open-access journal has 2 articles on the Apdex Performance Index:

1. "The Apdex Index Revealed", by yours truly
   
2. "The Apdex Index vs Traditional Management Information Decision Tools", by Jim Brady
   

Jim's article compares the Apdex Index with other well-established management decision techniques; especially those based on statistical methods. As someone with a background in Operations Research, Jim is well placed to make these assessments. It's worth noting that Jim's paper arose out of PARS discussion he and I had at CMG'08 in Las Vegas. PARS stands for Performance Analysts' Relaxation Session (a play on mainframe LPARS) but most CMG-ers just think of it as a "free" food and booze session. ;-) I was relating to Jim that I had attended a couple of CMG presentations which tried to explain the deeper significance of the Apdex Index definitions and there were a few things that really bothered me. I thought he might be able to explain it to me in terms of mathematical statistics. We didn't resolve anything that night (what can you expect with all that booze around?), so I left it with him as homework. His paper is the outcome. You'll have to read my article to find out what was bothering me. :-)

NorCal CMG Meeting Location

For those of you who haven't attended before, the Feb 3rd (Tues) meeting of the Northern California CMG will be held in Suite 100 of the Compuware building in Pleasanton, California. Here's the Google map. Three talks will be presented:

• 9:30--10:30 Mongo Measurement Requires Mongo Capacity Management, Neil Gunther, Performance Dynamics Company
  
• 10:45--11:45 Wasted MIPS, Wanton MIPS: a MIPS Recovery Initiative, Tom Halinski, Compuware Corporation
  
• 1:00--2:00 The Apdex Index Revealed, Neil Gunther, Performance Dynamics Company
  

Breakfast starts at 8:30 am and registration is $25 at the door.

NorCal CMG Meeting Feb 3, 2009

If you're in the neighborhood, I'll be giving two talks:

1. "Mongo Measurement Requires Mongo Capacity Management"
   
2. "The Apdex Index Revealed"
   

at the next meeting of the Northern California Computer Measurement Group.

Apdex Meets Apex

The Apdex Alliance has defined a performance metric, called the Apdex index, which rates the measured response times of distributed applications from an Internet user perspective. The Apdex index is constructed from three categories which are defined by partitioning the total number of sample counts (C) according to an agreed upon threshold time (τ):

1. Satisfied (0 < S < τ)
2. Tolerating (τ < T < 4τ)
3. Frustrated (F > 4τ)