please see the below resource
Q: What are metrics?
A: A metric is a measurement. While it's easy to count things that are easy to count, and to divide the counts by other things that you count, it's harder to decide what the counts and ratios mean. What are we trying to measure, and what model and what evidence lead us to believe that the counts measure the attribute we claim to be trying to measure?
Without clear thinking about validity, the numbers are more of a dangerous distraction than a useful tool. Rather than blindly using a well-known metric, decide what goal you are trying to achieve and find out how best to measure to achieve that goal.
Not everything that can be counted counts, and not everything that counts can be counted.
Albert Einstein
Questions you must ask before starting to use metrics are:
* Who will use these metrics?
* What behaviour are you trying to promote with these metrics?
* What information is important to know across the project?
* What requires increased visibility or transparency?
Please see
http://www.kaner. com/pdfs/ metrics2004. pdf
and
Measuring and Managing Performance in Organizations
Robert D. Austin
ISBN: 0932633366
http://sunset. usc.edu/classes/ cs577b_2001/ metricsguide/ metrics.html