Identity Resolution
Identity resolution is the process of connecting multiple identifiers and data points across devices, channels, and sessions to create a single, unified profile for each individual user.
Also known as: identity stitching, user stitching, cross-device identity, ID resolution
Why It Matters
The average person uses 3-4 devices and interacts with brands across dozens of touchpoints. Without identity resolution, each of these touchpoints looks like a separate anonymous user. A single customer might appear in your data as five or six different visitors - browsing on their phone, researching on their work laptop, and purchasing on their home desktop.
Identity resolution solves this by linking deterministic identifiers (like email and user ID) and probabilistic signals (like device fingerprints and IP patterns) to build a unified customer profile. This dramatically improves the accuracy of your metrics. Your actual unique visitor count may be 30-40% lower than what cookie-based analytics reports because many "unique visitors" are the same people on different devices.
Beyond accuracy, identity resolution enables cross-device attribution, allowing you to credit the mobile ad that started the journey even when the conversion happened on desktop days later.
Industry Applications
A multi-channel retailer uses identity resolution to discover that 42% of customers who purchase in-store previously browsed the website, allowing them to properly credit digital marketing for offline sales.
A SaaS company resolves that their average buyer touches 7 different marketing channels across 3 devices before signing up, changing their attribution model from last-click to multi-touch.
How to Track in KISSmetrics
KISSmetrics performs deterministic identity resolution automatically. When a user is identified via the identify method on any device or channel, KISSmetrics merges all previous anonymous activity from that device with their profile. If the same user is identified on a second device, all activity is unified into a single person record. Use the People report to verify that identity resolution is working correctly.
Common Mistakes
- -Relying solely on probabilistic matching (IP address, user agent) which can incorrectly merge distinct users, especially in office networks.
- -Not calling the identify function early enough in the user journey, leaving too much activity unresolved.
- -Merging identities incorrectly when multiple people share a device, such as a family computer or a shared work login.
- -Assuming identity resolution is a one-time setup rather than an ongoing process that needs monitoring and refinement.
Pro Tips
- +Prioritize deterministic matching (known identifiers like email and user ID) over probabilistic matching for accuracy.
- +Create incentives for users to identify themselves early - email-gated content, saved preferences, or wishlist features.
- +Audit your identity graph regularly to catch and fix incorrect merges, especially for users from the same household or company.
- +Implement server-side identity resolution as a complement to client-side to handle scenarios where JavaScript tracking is blocked.
Related Terms
User Identity
User identity in analytics refers to a unique identifier - such as an email address, user ID, or account number - that links a specific real person to their tracked behaviors and interactions across sessions and devices.
Cross-Device Tracking
Cross-device tracking is the ability to follow and connect a single user's activity across multiple devices - such as smartphone, tablet, and desktop - into one unified behavioral profile.
First-Party Data
First-party data is information collected directly by a company from its own customers and website visitors through owned channels, including behavioral data, purchase history, and voluntarily provided personal information.
Cookie
A cookie is a small text file stored by a web browser on a user's device that allows websites to remember information between page loads and across visits, widely used in analytics to identify returning visitors.
Campaign Attribution
Campaign attribution is the process of assigning credit for a conversion or sale to the specific marketing campaigns, channels, and touchpoints that influenced the customer's decision, enabling marketers to understand which efforts drive results.
See Identity Resolution in action
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