Keystone or Tombstone
A keystone metric is a measure of the primary action that you want your site to deliver.
A tombstone is what you may as well put on your website if you don’t have a keystone metric in place.
A keystone metric tracks the 1-2 primary actions that you want any visitor to your site to do. They are your site’s reason for being. All of the pages work together in concert to bring about these actions.
For our work on Palantir’s site, the keystone metric was the number of high-quality leads received by the sales team.
For our work on Sweetgreen’s site, the keystone metric was monthly revenue.
A good keystone metric should map directly to a specific business outcome. Something that, when successful, can be truly celebrated by your whole team.
If the site doesn’t deliver on its keystone metrics, it is a failure and needs adjustment.
Common Mistake 1
Your keystone metrics must not be a generic website metric like “time on site” or “number of page views.” These are secondary metrics. They are valuable and can help in diagnosing any performance issues with respect to your site objective, but they are just signals. They are not an outcome. And for your site to be an investment, not an expense, you have to stay focused on outcomes.
Common Mistake 2
Your site cannot have more than two keystone metrics. Beyond that, you will be forced to make compromises at almost every turn to keep both objectives in view / balance. This leads to two outcomes with mediocre metrics instead of one with outstanding performance.
This is not to say that other metrics will not benefit from your web system. But for the greatest impact, focus on one and the spillover benefits will be a wonderful pile of cherries on your sundae.