Fifty Words for Source: Understanding All 200 Traffic Dimensions in GA4 - Part 1

There are a multitude of options available to us when it comes to acquisition reporting in GA4, with many of the standard dimensions you’d expect now split out by scope and platform. This can make it tricky for analysts and marketers to work out where, when and how to use these dimensions.

In this blog series, we’ll walk through each of the options available, explaining what each variant does and highlighting use cases as we go along, starting with the basics: Source, Medium, Campaign and beyond!

Introduction

If you’ve spent any time exploring filters, comparisons, segments, or custom explorations in GA4, you’ve likely noticed the overwhelming number of available acquisition dimensions.

The Google Analytics support site currently lists 118 dimensions under the subheading of Traffic Source (how users are finding their way to your site or app) plus another 78 dedicated to Attribution (how credit for key events is shared back to these channels). Once we factor in options for custom channel groupings, that’s around 200 ways to slice and dice your traffic reports!

It’s understandable then that newer users to the platform may feel a little out of their depth, which is why we at Jellyfish have put together this series of blogs, each focussed on understanding and using a different group of these dimensions.

First off, the essentials!

Source, Medium and Campaign in GA4

These are the three core acquisition dimensions all analysts and marketers using Google Analytics know and love. We’ve written about these before in the context of GA4’s default channel groupings. In short, they reflect the values set by the browser for organic traffic or those defined by your campaign tagging - either automatically or via manually added UTM parameters for paid media.

• Source: From the referrer or utm_source. The specific location from where a user was referred to your site. For referrals from around the web this will appear as the full domain the user came from (e.g. ‘careers.myexamplewebsite.com’), while known search engines will appear, Cher-style, under a single name (‘google’, ‘baidu’, ‘bing’, etc). When there is neither a referrer nor campaign tagging, as when a user comes from an untagged, offline link, a bookmark or by typing the address straight into the browser, this will appear as ‘(direct)’.

• Medium: From the referrer or utm_medium. A broader classification of sources by ‘type’. Most of your traffic will be split into one of ‘cpc’ (paid), ‘organic’ (organic, naturally) or ‘referral’ (untagged links from around the web), but you may choose to create your own mediums for channels such as email, sms and out-of-home. When there is no way for GA4 to classify this traffic, the medium will be ‘(none)’.

• Campaign: From utm_campaign. Relevant for paid media only, this pulls through the name of the marketing campaign the link was associated with.

In GA4, Source, Medium, and Campaign (among other dimensions) are now split into several variants, organized by their scope and the linked platform they originate from. As a result, the full dimension name might look something like:

This means in place of a single Source dimension you will now find a whole host of different Source dimensions available, such as First user SA360 source, Session Google Ads source or (Event-level) Manual source.

Though we will cover scope and platform-specific variants in future blogs, for now the most important consideration when working with traffic dimensions in GA4 is consistency: when you analyse your data, make sure that you are comparing dimensions of the same scope and type.

For most common use cases, if you’re unsure where to get started, it can help to stick to the variants set at Session scope that don’t explicitly name a platform (so ‘Session source’, ‘Session medium’ and ‘Session campaign’), as these most closely match what you would have used in earlier version of Google Analytics.

How to use Source, Medium and Campaign

The various Source, Medium and Campaign dimensions give you the ability to break down your traffic in any number of ways. We can analyse our top performing channels overall or see the performance of a specific subset, such as finding our top paid traffic sources by filtering by Medium = ‘cpc’, or seeing where from around the web users are being linked by filtering by Medium = ‘referral’.

With proper governance over our campaign tagging we can go further. Many businesses maintain a campaign tagging builder spreadsheet to enforce naming conventions within individual fields such as Campaign so that they are more easily broken down into delimited components, for example ‘[campaign name] [flight dates] [targeting conditions]’, allowing you to do more granular analysis (‘What was our most successful Black Friday campaign?’, ‘What channel drives the most prospects to the site?’) with just these three sets of dimensions.

In addition, Google kindly provides a two-for-one in the form of a set of concatenated Source/Medium dimensions. Since the standard reports only allow for two dimensions on screen at a time, having one of these as your primary dimension gives you a handy way to break down traffic by Source, Medium and Campaign in one go (as per the image below).

It’s worth mentioning that this two-dimension restriction is not in place when building a free-form exploration, where you can go wild and add up to 5 dimensions to your table!

Less known traffic dimensions in GA4

There are a handful of other, less used, traffic dimensions at our disposal. Many of these are only relevant for certain subsections of our traffic, such as users who came to the site via a specific marketing platform, but they are still capable of providing valuable insights.

These include the following:

• Source Platform: From utm_source_platform. The marketing platform the ad was managed via, such as a GMP product, or a Google Shopping listing. Available as a primary or secondary dimension in the standard reports, and in custom Explores.
• Campaign Id: From utm_id. A unique identifier for your paid media campaigns. In practice, you’ll want to use the more human-readable campaign name dimensions (the ones ending ‘... Campaign’) in your reports, but a consistent Campaign Id is still useful as a backup if there is any chance a campaign name might change, as well as being a good key to match against when importing additional impression, click and cost data from your non-GMP campaigns into GA4. Available as a secondary dimension in the standard reports, and in custom Explores.
• Ad Content: From utm_content. Can be used to distinguish between creatives with the same destination link, such as images in a carousel ad, or a header and footer link in an email. As such, it can be used to quantify the results of AB tests and other Conversion Optimisation experiments you may be running in your ad campaigns. Only available in custom Explore reports.
• Term: From utm_term. Paid search keyword. Use it to better understand and improve your bidding strategy. Only available in custom Explore reports.

We also have a couple of new utm parameters lined up for future use:

• Creative format: From utm_creative_format. Type of creative, such as display, native, video or search.
• Marketing tactic: From utm_marketing_tactic. Targeting criteria for a campaign, such as prospecting or remarketing. Not yet available in the interface.

These dimensions are still being rolled out, but should already be available in the GA4 data schema in BigQuery. It’s likely that when they do become readily available in the reporting interface they will follow the same Scope - Linked platform - Dimension structure as other traffic dimensions.

If you can’t wait until they become available, you may want to look into creating custom dimensions to collect them at the User, Session and Event scope, allowing you to see what channels are driving discovery, retention and conversion, respectively: something we will explore in more detail in the next blog in this series!

In conclusion

We have seen that GA4 provides us with plenty of ways to analyse traffic to our site straight out of the box, from the classic Source, Medium and Campaign, to other dimensions like Source Platform, Ad Content and Term. Each of these gives us an unique way to split out our users for analytics reporting, retargeting and more advanced use cases such as importing and matching non-GMP campaign data back to conversions using Campaign Id.

We also saw how we can further tailor these fields to our business through a well-thought out campaign tagging strategy and the creation of custom dimensions. But this is only the beginning, and there is plenty more you can do working with the different subsets of each of these dimensions, by scope and by product, subjects we’ll return to in future blogs.

Want to learn how you can use these dimensions in your account? Our GA4 training courses provide hands-on experience working with these dimensions and more. Whether you’re newer to GA4, looking for more advanced learning, or want to build dashboards in Looker Studio.