"Know before you count" is a software development management principle simply stated by Gerald Weinberg as, "Before you can count anything, you've got to know something." He is talking about the many people who count things in software but don't know what they are counting. He provides a great example. We have data concerning what percentage of the software industry is involved with maintenance rather than development. But can we recognize maintenance? Is a "new" development that completely replaces an existing system considered maintenance or development? Is a "modification" to an existing system that doubles current functionality and removes 95 percent of old functionality considered maintenance or development?
When selecting metrics for your project, make sure that what you are measuring relates to what you are trying to achieve. This often entails using multiple metrics. Remember: Even if everybody is measuring something one way, that way is not automatically right for you. Think about your metrics. Since everything can be observed (and in most cases measured), carefully select what you want to observe (and measure).
References:
Stark, G., Durst, R., and Vowell, C., "Using Metrics in Management Decision-Making," IEEE Computer, September 1994.
Weinberg, G., Rethinking Systems Analysis and Design, New York: Dorset House, 1988.
