Megaphone is compliant with the IAB’s podcast measurement v2.1 guidelines. However, there are a lot of areas that are open to interpretation in the IABv2 guidelines, which can lead to discrepancies, even among third parties that are certified (Chartable and Spotify Ad Analytics). Download data is passed from the listening application back to Megaphone using the RSS feed, but the algorithm may process the information in a different way.
Factors that may cause Megaphone’s metrics to differ from third party attribution tools or listening applications include:
Implementation - Once the third party tracking prefix is implemented or enabled, they will begin tracking downloads. From the moment it’s been installed, it will collect downloads from that time forward, and the first day will have only partial data.
This also means that data for episodes released prior to the prefix being installed will differ, because there will be a gap between the time the episode was released and when they were able to begin seeing downloads.
Download windows - We define unique downloads on a calendar day in the UTC timezone per the IABv2 guidelines. Your listening application or third party attribution provider not may deduplicate unique downloads or may use a different time period for unique downloads, such as a rolling 24-hour window, a 1-hour window, or a 24-hour day in a different time-zone. This may cause a significant difference in the data you are seeing.
Blacklisted IPs and User Agents - We don't count all downloads from known datacenter IP ranges (e.g. AWS, Azure) or other IPs or user-agents that trigger our abuse detection systems. This affects some podcasts more than others. Some hosting providers may not use a blacklist, or may use a different one than ours.
Whitelists - The IAB guidelines allow vendors to implement a whitelist for known “high-density IP addresses” like dorms and corporations. We don’t use a whitelist due to the potentially error-prone process involved. Other measurement tools may differ.
Embedded players - Megaphone allows for analytics prefixes in the web-embedded episode players.