Medium

Medium is the traffic “how” — the general channel type that brought a visitor to your site. In attribution and campaign tracking, medium tells you whether the visit came via organic search, cpc (paid search), email, referral, social, display, affiliate, or direct. It’s typically populated by the utm_medium parameter in links and sometimes inferred by your analytics pipeline from referrers and ad click data.

Think of medium vs. source this way: medium = how, source = who/where. Example: google / cpc → medium is cpc, source is google. For campaigns, pair it with campaign to evaluate performance across channels.

Why medium matters

  • Clean, consistent mediums enable reliable channel-level reporting, budget allocation, and forecasting.
  • Medium is the backbone of acquisition dashboards and multi-channel funnel analysis.
  • Sloppy mediums (“Paid”, “paid”, “ppc”, “CPC_ads”) fragment data and destroy comparability.

Recommended naming (keep it lowercase and opinionated)

  • organic, cpc, display, email, social, referral, affiliate, direct
    Tie your taxonomy to a data contract and validate inputs at link-build time. See UTM Parameters.

Quick formula

Sessions by Medium = Σ sessions where medium = X
Conversion Rate by Medium = conversions with medium = X ÷ sessions with medium = X

Mini example

MediumSessionsConversionsConv. Rate
organic3,2001765.5%
cpc1,4501319.0%
email600183.0%

Interpretation: email underperforms; cpc converts well; organic drives volume. Next steps: shift budget toward high-ROI cpc terms, improve email offer and cadence, and protect organic rankings.

Implementation notes

  • Always set utm_medium explicitly in outbound links and ad URLs.
  • Normalize values to your canonical list on ingest; reject unknown mediums.
  • Map mediums to your channel grouping and content grouping for consistent reporting.
  • Don’t overload medium with network names (that’s source) or audience labels (keep those in campaign or term/content).