Any metric has associated value and costs.
The value of a metric is the difference between two decisions: one made with a metric and the other made without it. If it is equal to zero, then there is no point in having the metric, since the metric does not improve (or does not participate at all in) the decision. The costs of a metric are the costs of thinking through, implementing, and using the metric. Although the cost of metrics in online communities is kept to a minimum, metrics require interpretation and attention by a decision maker or an analyst. Any new metric you add creates yet another data point by itself and one more thing to look at. If metrics are not created wisely they add more noise to the data than there was prior to them and overwhelm the decision making person, reducing the value of having them at all.
If a metric has no value, there is no reason to have it.
This is a fragment of a draft of the book “Lessons Learned While Working On Stack Overflow”. Read the full book on kindle or the paperback version.