You Had One Job
Each individual page of your site (with the exception of your homepage) should have just one job. That job should be some sort of target “next action” we want the customer to perform.
The metric for any given page should most likely be “what percentage of the time did people who landed on that page do the target action.”
It’s that simple.
All other data about a given page is diagnostic, designed to help you understand why they may or may have not done the target action.
As you evolve your site, you can use these page metrics to see:
How a given page or category of pages is contributing to your keystone objective.
Whether a given page is still adding value or should perhaps be pruned.
Aspects of your story that are especially engaging to your visitors.
Example:
To understand the one job concept a little better, let’s talk about a typical Product Detail Page (PDP). The job of a PDP is not to fully complete the purchase flow. It can’t be responsible for all that.
The job of the PDP is to get you to add something to the cart. Then it’s the job of the cart to get you through checkout. If your cart is multiple steps, each step has the job of getting you to the next. This allows us to ultimately analyze the chain of steps to see where weakness / opportunities for improvement are.
As Fleetwood Mac says, the chain keeps us together.