An affiliate (affiliate partner/publisher) is a third-party that promotes your product and earns a commission for a verified action: a purchase, signup, or qualified lead. In web analytics, the Affiliate channel is traffic and conversions attributed to these partners. You control the rules via your attribution model, lookback windows, and de-duplication logic so you don’t double-pay with other channels.
How affiliate traffic is tracked
Affiliates use unique tracking URLs containing identifiers and UTM parameters. A click sets an identifier (cookie, local storage, or server-side session). When the user converts, your tracking pipes fire (client or server postback) and match the conversion to the affiliate ID. Good setups also pass subIDs for placement/creative and run fraud filters (bot clicks, coupon hijacking).
Key metrics and formulas
| Metric | What it tells you | Formula |
|---|---|---|
| Clicks | Traffic delivered | — |
| Conversions | Actions credited to affiliate | — |
| Conversion Rate (CR) | Efficiency of traffic | CR = Conversions / Clicks |
| Payout / Commission | Cost of the affiliate program | % of order or fixed per lead |
| Effective CPA | Cost per conversion | eCPA = Total Payout / Conversions → see Cost per Acquisition (CPA) |
| EPC | Earnings per click (program view) | EPC = Total Payout / Clicks |
| Average Order Value (AOV) | Basket size of affiliate sales | AOV = Revenue / Orders |
| Approval Rate | Quality after validation | Approved / Submitted |
Mini example
You have 5,000 clicks from affiliates and 150 purchases. AOV is $60. Commission is 8% of order value.
- Revenue from these orders:
150 × $60 = $9,000 - Total payout:
8% × $9,000 = $720 CR = 150 / 5,000 = 3%EPC = $720 / 5,000 = $0.144eCPA = $720 / 150 = $4.80
Implementation checklist
- Define attribution and lookback (e.g., last non-direct vs multi-touch attribution); enable de-duplication with paid search/retargeting.
- Enforce unique codes/links to prevent coupon leakage.
- Pass subID parameters for placement, creative, and geo to enable granular reporting.
- Monitor anomalies (spikes in clicks, low CR, sudden AOV drops).