What is SKAdNetwork (SKAN)?

SKAdNetwork (SKAN) is Apple’s privacy-first attribution and measurement solution for advertising campaigns run on iOS. SKAdNetwork in its original form was introduced in May 2018 as an optional API that would allow for attribution while preserving privacy. In April of 2021, however, when iOS 14.5 was rolled out along with the App Tracking Transparency framework (ATT), users were required to opt-in and provide consent to sharing of their user level data via Apple’s Identifier for Advertisers (IDFA). SKAdNetwork (then SKAdNetwork 2) became the only way for advertisers to attribute users who have not opted-in.

Now in its fourth iteration, SKAN 4 and all SKAN versions are, simply, another way to attribute advertising campaigns on iOS. It’s free for advertisers to use and is the cornerstone of Apple’s goal of providing privacy-focused attribution that doesn’t require user consent but is fully in line with its privacy guidelines. In practice, the attribution data from SKAN is relayed from the device to Apple and then to ad networks, developers, and mobile measurement partners (MMPs).

SKAN can be implemented by clients on their own, or with Adjust’s help. Adjust/the MMP’s role in this scenario is to put the pieces together by helping clients get the most of the data they receive so they can continue optimizing campaigns successfully and driving growth on iOS.

Up until SKAN 3, and available in SKAN 4’s Postback 1 for Measurement Window 1 (more below), SKAN provides space for 6-bits of downstream metrics, or a number between 0 and 63 (more specifically between 000000 and 111111 in binary). This number is known as a conversion value, or SKAN 4 fine grain conversion value, and can be assigned to any events or series or events that apps want to measure.

For SKAN 3, the measurement window is 24 hours, for SKAN 4 Postback 1 it’s up to 48 hours, and the postback containing the information will be sent at random—a minimum of 24 hours after the conversion value is last updated on SKAN 3 and 24-48 hours later for SKAN 4. The goal of the timers is to obfuscate (obscure or jumble) the time of install, making it impossible to link event triggers to individual users. The postback that’s received includes the conversion value and absolutely no user level data or device data.

Compared to traditional attribution methods and for iOS attribution on ATT opted-in users, SKAdNetwork poses significant measurement difficulties and challenges. The key complexity is in learning to extrapolate precise and actionable insights from the data received in the SKAN postbacks. In short, the main issues in doing this are:

• Less precision across the board: User acquisition (UA), attribution, and measurement of campaign performance are all significantly more challenging when working with SKAN because advertisers have less (or no) visibility into user level data and metrics. While UA and measurement with the IDFA is extremely precise and provides marketers with visibility into performance and the ability to operate within extremely thin margins, SKAN attribution means going back to the drawing board to create a new attribution strategy that focuses on aggregated data and predictive analytics. Without predictive analytics, there’s no real way to measure ROI or LTV, because SKAN attribution data is simply too limited—particularly SKAN 3.
• Delays in receiving data: With the delayed postbacks, making lightning fast optimizations to campaigns and budget allocation is not really possible. On SKAN 3, the postback delay is 24 hours after the timer is triggered, on SKAN 4, it’s between 24-48 hours after the end of Measurement Window 1 or after the point in each window where the lockWindow has been applied, and 24-144 hours after either of these points for Measurement Windows 2 and 3.
• Re-engagement measurement isn’t possible: Because no device- or user-level data is collected or shared, it’s not possible to measure or attribute re-engagements. We're hopeful this will become possible with SKAN 5.
• Working with conversion values: For SKAN 3, advertisers receive one postback with one conversion value based on the 0-63, 6-bits of downstream metrics. On SKAN 4, there are three measurement windows, the first of which can contain the same conversion value concept as on SKAN 3 (now named fine conversion values) or a coarse conversion value (high, medium, low), while measurement windows 2 and 3 can’t contain a fine value but may contain a coarse value. It’s essential that marketers learn how to link their strategic vision and core KPIs to the in-app events and revenue ranges that can be mapped to conversion values, as this is the only way to extrapolate insights from SKAN and drive sustained growth on iOS.

Released in October 2022 alongside iOS 16.1, SKAN 4 introduced a slew of new features for attribution and measurement of iOS campaigns.

These updates include:

1. Three measurement windows and three postbacks instead of one: Where SKAN 3 provides one postback based on a 24-hour measurement window, SKAN 4 provides three postbacks based on three measurement windows (0-48 hours, 3-7 days, 8-35 days). For the first measurement window, the postback is sent between 24-48 hours after the timer is triggered, whereas for the second two windows, the postback can be delayed anywhere between 24-144 hours.

One of the most common questions (other than how to successfully optimize SKAN campaigns) Adjust is asked by clients is how and when to make the move from SKAN 3 to SKAN 4, along with whether it’s possible to use both at the same time. The answer is that we recommend starting to test and measure with SKAN 4 as soon as possible and that, yes, both can be used simultaneously. In 2024, SKAN 4 adoption will continue to increase, making it essential that marketers and developers are fully leveraging it. As long as the publisher is signing their ads with the SKAN 4 signature, you’ll receive SKAN 4 postbacks. If they’re part-signing with both the SKAN 3 and SKAN 4 signature, you’ll receive both.

To fully leverage SKAN 4’s measurement capabilities, however, you’ll need to have a SKAN 4-ready SDK installed, for which Adjust was first-to-market in November of 2022. Without this SDK, you’ll only be able to receive fine values and will miss out on SKAN 4’s cornerstone coarse conversion values and lockWindow. Next up is to get a SKAN 4 configured conversion value set-up mapped and ready to go for all three of the measurement windows that allows you to leverage data signals, gain insights, unlock its full strategic potential, and transform it all into actions for campaign optimization.