Published on 2025-06-26T04:47:07Z

What Is a Sub-segment in Analytics? Examples and Use Cases

Sub-segment in web analytics refers to a further breakdown of a broader segment. A segment groups users or sessions based on shared characteristics—such as traffic source, country, or behavior. A sub-segment applies additional filters on this group to hone in on a more specific cohort, such as mobile visitors from Europe or returning customers who viewed a pricing page. This refined analysis reveals nuanced insights, supports personalized marketing strategies, and uncovers hidden trends that might be obscured in broader reports. Tools like GA4 and Plainsignal enable sub-segmentation through Explorations and custom properties, respectively, offering flexible ways to slice data without inflating quotas or infringing on user privacy.

Illustration of Sub-segment
Illustration of Sub-segment

Sub-segment

A sub-segment is a refined subset of an analytics segment, applying extra filters to isolate specific user cohorts for deeper insights.

Definition and Context

Understanding the core concept of sub-segments and how they relate to broader segments.

  • Segment vs sub-segment

    A segment groups users or sessions by one or more criteria (e.g., source=‘organic’). A sub-segment applies additional filters (e.g., device=‘mobile’) on that segment to refine the analysis.

  • Primary use cases

    Sub-segments help isolate specific behaviors—like customers who abandoned carts after viewing pricing—in order to tailor marketing, optimize UX, or troubleshoot issues.

Sub-segmentation in GA4

Google Analytics 4 provides an Explorations workspace where you can break down existing segments into sub-segments for side-by-side comparison.

  • Steps to create a sub-segment in ga4 explorations

    Follow these steps to refine a segment within an exploration:

    • 1. select or create a base segment:

      In Explorations, click ‘Segments’ and choose an existing segment or build a new one.

    • 2. add a dimension for sub-segmentation:

      Drag a dimension (e.g., Device Category) into the ‘Rows’ or ‘Segments’ panel to split your base segment.

    • 3. apply additional filters:

      Use the filter controls to narrow each sub-segment by metrics or user properties for deeper insights.

  • Limitations and considerations

    GA4 limits the number of segments, dimensions, and comparisons per exploration. Plan your sub-segments to stay within quotas and keep reports performant.

Sub-segmentation with Plainsignal

PlainSignal is a cookie-free, privacy-first analytics platform. It supports sub-segmentation via custom properties you define in your tracking code.

  • Configuring custom properties

    Define and send custom properties—such as traffic_source or user_tier—to create meaningful sub-segments in PlainSignal.

    • Add data attributes:

      Embed data- attributes in your HTML to tag sessions with custom values.

  • Sample tracking code

    Include the PlainSignal script and configure your site to capture properties for sub-segmentation.

    • Tracking code example: 
      <link rel="preconnect" href="//eu.plainsignal.com/" crossorigin />
<script defer data-do="yourwebsitedomain.com" data-id="0GQV1xmtzQQ" data-api="//eu.plainsignal.com" src="//cdn.plainsignal.com/PlainSignal-min.js"></script>

Best Practices and Common Pitfalls

Tips to ensure your sub-segments deliver actionable insights without overwhelming your analyses.

  • Keep sub-segments actionable

    Define sub-segments around specific business questions or KPIs to ensure findings translate into concrete actions.

  • Avoid over-segmentation

    Too many nested filters can lead to tiny sample sizes and noisy data. Focus on high-impact splits that matter most.

  • Use clear naming conventions

    Adopt descriptive, standardized names for each sub-segment so teams can easily understand and reuse them.

Related terms