Mobile App Terminology

Source identifier

What is a source identifier?

The term source identifier refers to a unique identifier that’s assigned to an advertising campaign or source in the SKAdnetwork mobile attribution framework by Apple, including the latest SKAdNetwork 4.0. The purpose of the source identifier is to enable marketers to track performance of ad campaigns and make more data-driven decisions about future campaigns.

Specifically, the source identifier (SID) is used to track the performance of an ad campaign and its impact on app installs, conversion events, and revenue. With the SID, markers are able to see which campaigns are driving the most installs and conversions and optimize their campaigns to achieve the highest ROAS possible.

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How do marketers use source identifiers?

In order to use the source identifier, marketers need to assign a unique SID in their ad campaigns, which can then easily be tracked by analytics and reporting tools like Singular. In particular, you should include the SID as part of your ad creative, which will allow SKAdNetwork to associate with the campaign and track its performance.

As highlighted in our guide to SKAdNetwork 4.0, there are other several changes to how source identifiers are used that marketers should be aware of. For example, the new framework has lockable postback windows, which allows the conversion value to be “locked in” and finalized earlier.

For example: someone makes a purchase in your retail app on D0 or D1 (essentially immediately). You can lock the conversion value then, and kick off a postback immediately. For example, an advertised app can successfully generate a conversion event that the marketing and product teams view as significant enough to want to know about ASAP. This event happens at some point before the end of the second postback period, so it’s locked and sent immediately.

With regard to the data marketers can encode into source identifiers, Apple’s newest SKAN 4 framework now takes crowd anonymity into account when deciding how much data to share with advertisers. If the “crowd” is small, or your ads are only going to a small audience, you might only get 2 digits in your source identifier: enough to measure 100 campaigns.

Only when the crowd or population of ad-receiving people for a specific campaign is large will marketers get 4 digits of source identifier in SKAN 4. That will enable not just campaign identification, but also provide details around geo, creative, and other parameters that can help ad networks and marketers optimize campaigns.

As Apple highlights in their documentation on hierarchical source identifiers:

Ad networks can now provide hierarchical source identifiers when they sign an ad, which replaces and expands on campaign identifiers. The source identifier is a four-digit integer, which you indicate in sourceIdentifier for view-through ads and in SKStoreProductParameterAdNetworkSourceIdentifier for StoreKit-rendered ads. Winning postbacks contain two, three, or four digits of the source identifier, depending on the ad impression’s privacy threshold tier.

In short, the source identifier is an essential part of the SKAdNetwork 4.0 framework that allows marketers to track the performance of their campaigns while still preserving user privacy.

How does Singular help marketers work with source identifiers?

As a leader in marketing analytics and mobile attribution, Singular allows marketers to automatically assign and track SIDs. With this data in hand, marketers have the data they need to optimize the performance of ad campaigns and achieve the highest ROAS possible. 

Below are several strategic decisions to consider as you transition to the new framework as highlighted in our SKAN 4 strategy guide:

  • Strategic decision 1: building your conversion value models
  • Strategic decision 2: be willing to adapt, because Singular gives you free model flexibility
  • Strategic decision 3: to use conversion locking or not
  • Strategic decision 4: choosing when to set up your SKAN 4.0 models in Singular 

For further support in your transition to SKAN 4, you can get in touch today and we’ll be happy to help you every step of the way.

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