95th percentile - the sociology study.

Jo Rhett jrhett at svcolo.com
Mon Feb 27 20:10:29 UTC 2006

I didn't realize when I asked for how people handled a mathematical
function for billing purposes, that the results would be more interesting
to a socialogist than a network provider. I figured 
	How do you (not how do I)...
would be pretty specific, but apparently I underestimated the interesting 
ways that would be misread.

7 people wrote me with exactly the answers to the questions I asked. Nice.

7 people wrote to tell me how to calculate 95th percentile, but didn't
include answers to any of the questions I asked.
	* On reply/request 5 of them did eventually answer the questions

4 people wrote to tell me how to calculate 95th percentile, but did
remember to answer the questions I asked.

2 people wrote to tell me I was doing it wrong, and that I didn't
understand what 95th percentile was.
	* Both of them eventually admitted that they don't work in a place
	which calculates 95th percentile for their customers.

The remainder of my 20 samples were offlist queries/conversations with other 

Some rough statistics from an admittedly small sample:

1/3 of the nanog repliers understood the question and knew how to answer
it.  Hmmm.  Nanog clue level is definitely improving.
All but three of the people who tried to teach me how to calculate 95th
percentile were polite and clueful when I reminded them that I wanted the
math, not a tutorial.  A couple of misunderstanding actually wandered off
into statistical analysis ramblings which was an amusing offset to the
next set.

Only three of the people insisted on telling me I was doing it wrong 
(never posted how we were doing it in the first place, so this was amusing) 
and tried to clue by four me into their approach.

  2 did the math wrong in their long rants sent back to me ;-)

  1 tried to convince me that modern equipment can't handle being sampled
     more often than every 5 minutes.
And all three that tried to argue with me showed in their analysis that
they don't deal with anything approaching 100Mb peering, nevermind 1g or 10g.

And for those of you who can count, yes, one of the people who tried to
teach me how to calculate 95th percentile didn't respond back either
positively or negatively when I tried to remind him of the questions asked,
and one was rude. (I don't blame him, after the 10th or so reply I was too)

For statistical analysis:

2 women responded.  Unfortunately one of them disagreed with a male
counterpart from the same company and when I asked them to clarify it turns
out the guy was right. (the girl's math was excellent, but based on an
incorrect assumption. stereotype reversal in action)

Jo Rhett
senior geek
SVcolo : Silicon Valley Colocation

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