Marketing Attribution 102

User vs Event Properties

Event properties in Amplitude are attributes of your user’s events. These properties do not extend beyond the specific event.

User properties in Amplitude do not need to be sent with every event. Once a user property is set its value persists and Amplitude applies it to all subsequent events until the value changes.

The attribution properties managed within browser SDK 2.0 leverage user properties. Here’s why:

When a user enters your application from bing.com via organic search, you probably want to continue to give credit to bing.com until another marketing tactic is introduced or until the session ends. By relying on user properties that value can be set and then persisted until replaced rather than having to be stored in a client and sent with each event.

Leveraging user properties in lieu of event properties for channel-classifier properties enables last-touch-esque attribution throughout the platform in lieu of the need to solely rely on attribution models within a data table.

Identify API

The Identify API is an Amplitude feature to update user properties for a specific user without sending an event. Attribution leverages three of Amplitude’s user property operators.

$setOnce

Set the value of the property only if the value hasn’t already been set.

With $setOnce the application does not need to maintain awareness of a user’s history. Amplitude’s servers will evaluate if there is an existing value for a given user property. If there is, the new value will not overwrite the original value.

$set

Sets the value of the property.

$unset

Removes the value of the property.

$unset allows one to discontinue the persistence of a user property when it is no longer relevant.

Scenario:

A user visits your site from facebook.com and the SDK detects that via the referring domain. Later the same user visits the site with an email campaign that is identified by a utm_medium=email, and without a referring domain value.

By using the $unset operator facebook.com will not continue to receive credit for the subsequent email campaign.

By default Amplitude’s Browser SDK 2.0 manages attribution concepts for 19 marketing identifiers. For each of these 19 properties there are two user properties, which is addressed later in this post.

• UTM Parameters
  • UTM Parameters can be added to urls by anyone, but are generally a combination of marketer logic and platform derived values. The first parameter is added with a ‘?’ any subsequent parameters with an ‘&’.
  • example: https://amplitude.com/get-started?utm_source=google-ads&utm_medium=cpc&utm_campaign=Search_AMER_Brand&utm_content=707830940836&utm_term=amplitude&gad_source=1
• Referrers
  • Referrer is the term used to describe an optional field that is transmitted via the HTTP header when a web page is requested from a server. Loosely it represents the page that routed a user to the current page, if applicable.
  • This is generally collected via the JavaScript variable document.referrer in the browser.
• Click identifiers
  • Click identifiers are added to urls by the marketing platform. The first parameter is added with a ‘?’ any subsequent parameters with an ‘&’.
  • example: https://amplitude.com/get-started?utm_source=google-ads&gclid=Cj0KCQiAu8W6BhC-ARIsACEQoDBO-yDVCQstX56lQvCgVl6RnzfI9vZloqxVWHUykumq44YyHxwtCk8aAgm1EALw_wcB

Marketing attribution generally refers to the external tactics that motivate users to reach an application. To evaluate which referrers are considered internal and should be ignored for attribution Amplitude accepts inputs to the ‘config.autocapture.attribution.excludeReferrers’ parameter. By default the SDK will update this parameter to include the top level domain with cookie storage enabled.

In addition to the default value, . Two common use cases:

• An organization uses a third party payment processing site.
  • A subdomain like checkout.stripe.com should be listed in excludeReferrers to prevent marketing credit being assigned to the processor.
• An organization uses social sign-in features from google, apple, or facebook.
  • Subdomains like accounts.google.com or accounts.youtube.com may be listed in excludeReferrers to ensure they don't receive attribution credit.
• Tip: Including a custom value overrides the default settings. If you add any custom values also include your owned domain/subdomains in the exclusion list.

Browser SDK attribution relies on the ability to set and read from two cookies; the ‘user session’ cookie ‘AMP_{first_ten_digits_API_KEY}’ and the ‘marketing campaign’ cookie ‘AMP_MKTG_{first_ten_digits_API_KEY}’.

These cookies allow the SDK to evaluate session context and to evaluate if marketing attributes were updated.

Note: The ‘user session’ cookie does not expire after a session. This cookie can be thought of as the ‘identity’ cookie as it maintains the device_id.

initial_[marketing_attribute]

The user_properties prefixed with ‘initial_’ represent the user's first-touch marketing tactic.

These values persist beyond Amplitude’s 365 day maximum lookback window for first-touch attribution.

The SDK uses the $setOnce operator for these properties. While you may see initial_[marketing_attribute] values more than once in the $identify events the original value will not be overwritten on Amplitude’s servers.

Values that are not available receive a string value of “EMPTY”. This is to ensure that if the value for a property wasn’t initially present it doesn’t receive credit at a later time.

[marketing_attribute]

The version of the user properties without the ‘initial_’ prefix can be used for last-touch and multi-touch attribution.

These properties are maintained in relationship to one another. If a new utm_medium is introduced and a referring domain is not available the utm_medium will be updated with the $set operator and the referring_domain will be updated with the $unset operator.

Two additional optional features are available in the .

1. config.autocapture.attribution.resetSessionOnNewCampaign
   1. Configures Amplitude to start a new session if any marketing attributes changed. By default this is set to false. Changing this to true allows organizations to evaluate attribution similarly to Google’s Universal Analytics, where the introduction of a new campaign instantiated a new session.
2. config.autocapture.attribution.initialEmptyValue
   1. Allows you to set the value that is used to represent an attribute not being available in the initial_[marketing_attribute] properties. By default this value is “EMPTY”.

One of Amplitude’s greatest strengths is that we are an open ecosystem. Customers can ingest data through CDI’s, directly through warehouses, or via API.

While the content above focuses on the Browser SDK 2.0 it illuminates core concepts that organizations need to consider when ingesting data for attribution use cases.

1. For many organizations attribution requires session-awareness, specifically the ability to update attribution differently at the start of a session versus mid-session.
2. A separate property should exist for only those referrers you consider external to your platform. In addition to your owned domain(s) this should include any partner applications that a user encounters during their journey with you, like payment processors and social logins.
3. Attributes must be updated in relation to each other to prevent over-persistence.