Sorry for taking so long to respond. I work full time and go to college full time and just got sidetracked.
The reason why I ask to have the Median calculated along with the Mean (or Average) is that it tells me a whole lot about what a particular process is doing within the time interval.
To calculate the Median value, you order all the values from smallest to largest and pick the value dead center. (See attached GetMedian.ps1 file).
For example 1, 1, 2, 2, 3, 3, 3, 3, 4, 448.
The value that is at the halfway point is between the values at position five and position six. Basically (3+3)/2. If there were 9 values here, we would just settle for the midpoint value.
Let’s take an Avg. Disk sec/Read as an example. If we were to take the ten values listed above, we would end up with a Mean (average) of 47ms and a Median of 3ms.
As you can see, the Mean value of 47ms is skewed (because of the single high value of 448). A Mean of 47ms doesn’t necessarily mean that the
Avg. Disk sec/Read is at 47ms half the time. However, the Median of 3ms does tell me that the
Avg. Disk sec/Read is at 3ms or less half of the time.
For a quick starter on Median and Percentiles see this site:
http://devnambi.com/archive/2011/03/statisticalanalysis102medianpercentileandcovariance/
Also, Median is the same as the 50^{th} percentile. The GetMedian function could be adapted to find and return the top 99^{th}, 95^{th}, and 90^{th} percentiles.
I would love to take a shot at updating the code, but I just don’t have a lot of spare time right now as it is. I have two more semesters before I’m done and then I start on my Masters. If I catch a break in between
semesters, I might take a shot at it.
Thanks for your time.
