It’s not always trivial to determine the impact, or the lack of impact, of a change. However numbers don’t lie and we humans are used to be measuring everything except t-shirts with numbers. Measuring something in a numeric form before and after a change should indicate whether the change is good, bad, or ugly, right?
Metrics are those quantitative assessments of relevant items. Metrics are simple; when the value of a metric changes to one direction it’s good, and when the value changes to the opposite direction it’s bad. Assessing the metric over and over again in different times and analyzing the assessed results one could argue if things are getting better, worse, or being stable. And everyone wants things to be better!
To be able to compare the evolution of the metric the measurements of the value needs to be well-defined and repeatable.
But what actually should be measured?