Key Result metrics allow you to quantify Key Results and automatically track the progress of your Objectives. Simple OKR offers five types of metric types.
Milestone metric lets you track binary outcomes. You either reached your milestone, or you didn't. Use this metric when you can't express your Key Result as a numeric value. It is often the case when you are just starting out with OKRs and most of your Key Results milestones.
Baseline metric lets you capture a baseline value for a metric. Imagine a scenario where you want to track coupon redemptions with a goal to optimize coupon usage. When starting out, you may not have an available coupon redemption rate. You want to capture baseline value first before you can start work on improving coupon performance.
Positive metric lets you move toward a specific target value. Use this metric when more is better. An example could be "sign 100 new customers". Your target would be 100 customers, and starting value is probably 0. You can track the total number of customer signed throughout the quarter.
Negative metric lets you move toward a specific target value. Negative metric is similar to the Positive one; however, the metric value moves toward a smaller target value. Use this metric to track things such as risk and cost reductions. You can use this metric to track anything where you want to go from higher value to a smaller one.
With range metric, you can establish a range within which you want your metric to stay. You can use this metric to capture things like weekly resource utilization, or weekly spend.