Tag: quality

Agile Metrics Grid

Recently, Gerald Heller an I discussed about metrics used in agile development, agile testing metrics in particular. We found quite a number of relevant metrics and sought a way to structure them. Partly inspired by Brian Marick’s testing quadrants (see Lisa Crispin’s presentation), we ended up with a matrix spanned by two dichotomous axes.

The first axis (horizontal axis) distinguishes between coordinative and analytical metrics usage. Coordinative metrics are well-suited to directly support project activities, information needs, and decisions. Examples are tracking of work item status or burndown. Analytical metrics are used as input to investigations and analyses as they are conducted, for instance, in iteration retrospectives. An example is story cycle time, which shall be investigated at the end of a release in order to look for improvement opportunities for subsequent releases.

The second axis (vertical axis) distinguishes between internal and external metrics target groups. Internal target groups are the members of an agile software development team. External target groups are other stakeholders such as development management and product management.

The following figure shows our proposed agile metrics grid along with a number of categorized agile metrics. The grid helps guiding metric definition and clarifying the role that a given metric plays for agile development.

The agile testing grid is described in more detail in issue 4 of Agile Record, a magazine for agile developers and agile testers.

http://www.agilerecord.com

Goal/Question/Metric (GQM)

Goal/Question/Metric (GQM) is an established and elaborated method for measurement in software engineering. I have been using it, and doing evaluation research and method development on it since the 1990-ies. It can be useful in particular for the following purposes:

  • Systematically define measurement and reporting in software projects
  • Consolidate existing “ad hoc” measurement
  • Gain information needed for proces improvement and agile retrospectives

There have been reported many applications of GQM. Unfortunately, some involve misinterpretions of the method. For this reason, I propose in this article a few references and hints that can provide you with guidance and examples on how to apply GQM effectively.

GQM includes a data structure, the so-called GQM tree, that helps identifying and interpreting metrics for a given measurement goal. Specific types of questions clarify certain aspects of the measurement goal. Another data structure, the GQM Abstraction Sheet, facilitates handling of goal, questions and metrics.

Whenever I need metrics or reporting information about a piece of software or a software project, I find it highly useful to follow the GQM method in a pragmatic manner, to clarify what information exactly is required, how it can be obtained, and what needs to be considered when interpreting the data. Important GQM principles that provide guidance are:

  • Use the GQM goal template to clarify what shall be found out, and to what target group the information shall be directed.
  • Use only one or very few levels of Questions in order to keep the GQM tree concise.
  • Use exactly one level of metrics. If metrics tend to become complex, ensure that their definitions are clear and precise.
  • Focus on defining appropriate graphical representations of metrics information.
  • Be aware that the metrics data is only the raw material of measurement. Most important is the interactive data interpretation together with the GQM goal’s target group. This collaborative data interpretation is guided by the previously defined GQM questions.

The following literature gives a good overview of GQM. The article by van Latum et al. illustrates practical GQM application. The book by van Solingen and Berghout gives rich additional practical advice. The articles by Basili, Caldiera, and Rombach can be regarded the original source of GQM, although the method goes back to earlier work by Basili and Weiss from the 1980-ies.

Frank van Latum, Rini van Solingen, Markku Oivo, Barbara Hoisl, Dieter Rombach, Günther Ruhe. Adopting GQM-Based Measurement in an Industrial Environment. IEEE Software, pp. 78-86, January/February, 1998. (http://www.computer.org/portal/web/csdl/doi/10.1109/52.646887)

Rini van Solingen, Egon Berghout. The Goal/Question/Metric Method. McGraw-Hill Education, 1999. (http://www.iteva.rug.nl/gqm/GQM%20Guide%20non%20printable.pdf)

Victor R. Basili, Gianluigi Caldiera and H. D. Rombach. The Goal Question Metric Approach. In Encyclopedia of Software Engineering (John J. Marciniak, Ed.), John Wiley & Sons, Inc., 1994, Vol. 1, pp.528–532.

V. R. Basili, G. Caldiera, and H. Dieter Rombach. The Goal Question Metric Approach. NASA GSFC Software Engineering Laboratory, 1994. (ftp://ftp.cs.umd.edu/pub/sel/papers/gqm.pdf)