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Ratio

Overview​

A Ratio metric compares two related metrics by dividing one value (the numerator) by another (the denominator). This creates a normalized measure that reveals the relationship between the two quantities rather than their absolute values.

Ratio metrics are useful when you want to understand efficiency, conversion, quality, or per-user averages, because they remove scale effects and highlight how one metric behaves relative to another.

Examples​

Suppose you track the following events:

context.track("click", {
  element: "add_to_cart",
  product_id: "ABC123"
});

context.track("page_view", {
  page: "product_detail",
  product_id: "ABC123"
});

You could build a Click-through rate ratio metric defined as:

  • Numerator: Clicks per visitor
  • Denominator: Page views per visitor

This produces a meaningful relative measure that answers: “Out of all page views, how often do users click the add-to-cart button?”

More examples:

  • Average revenue per order -- Numerator: Revenue -- Denominator: Orders

  • Purchases per active session -- Numerator: Purchase count -- Denominator: Session count

  • Errors per request (for performance / reliability metrics) -- Numerator: Error events -- Denominator: API requests

  • Unique products purchased per purchaser -- Numerator: Goal Property Unique Count (product_id) -- Denominator: Unique purchasers

In all cases, the ratio reveals relative performance rather than total scale.

Good to know​

  • Ratio metrics are derived metrics: they depend on two other existing metrics.
  • They allow you to normalize behaviors across traffic volumes, user counts, or content types.
  • Fluctuations in either numerator or denominator can change the ratio — interpreting ratios requires understanding both sides.
  • They are highly effective for comparing efficiency (e.g., clicks per page view), value (e.g., revenue per user), or quality (e.g., errors per request).
  • Outlier settings, goal filters, and definitions of numerator and denominator are inherited from their underlying metrics.
  • A ratio metric does not directly count events — instead, it evaluates the relationship between two already-defined metrics.
  • Changes to numerator or denominator definitions typically require versioning, since a ratio metric’s meaning depends entirely on those definitions.