Customer Effort Score (CES) measures how easy or hard a customer found it to complete a task — usually framed as: “The company made it easy for me to handle my issue” on a 1–7 scale. Research from CEB / Gartner consistently shows CES as a stronger predictor of repurchase and loyalty than CSAT or NPS.
For customer portals specifically, CES is the most actionable feedback metric: if customers report high effort, you know the portal is failing them — even if their CSAT is acceptable. Common CES probe points: after support ticket resolution, after onboarding, after a self-service action like changing billing info.