Insights and custom alerts in GA4

This guide is built from Google's Analytics Help articles on Analytics Insights and anomaly detection, plus the Help pages on the Home page, data restrictions and scheduled emails linked below. GA4 has no separate "alerts" screen: the alerts are custom insights with an email notification. Setting up GA4 itself is covered in our GA4 basics guide, and watching traffic minute by minute in our Realtime report guide.

Automated and custom insights

Insights come from what Google calls Analytics Intelligence, "a set of features that uses machine learning and conditions you configure to help you understand and act on your data." It produces two kinds:

• Automated insights. GA4 "detects unusual changes or emerging trends in your data and notifies you automatically." You do not set anything up; they appear on their own.
• Custom insights. "You create conditions that detect changes in your data that are important to you." When a condition is met, the insight appears in GA4, and you can also get it by email.

Automated insights are a good way to spot things you were not looking for. Custom insights are for the few numbers you already know you care about, such as leads, purchases or traffic to a key page, where you want to hear about a change without opening GA4 every day.

Where insights show up

There are three places to look:

• The Home page. Its Insights & Recommendations section shows "unusual changes, emerging trends, and other insights about your site or app," according to Google's Home page article. Thumbs up or down on a card tells GA4 what is useful; dismissed cards can still be found in the full list.
• The Advertising snapshot. The Advertising snapshot report has an Insights card that "notifies you of significant changes or emerging trends in your advertising data."
• The Insights dashboard. Click View all insights on either card. Google says the dashboard "shows the most recent automated and custom insights for your property" and refreshes in real time as new insights are triggered. Click a card for details and Load more for older ones.

Google states that "insights are retained for one year after they are generated," and that GA4 learns from which insights you open and ranks new ones accordingly.

Creating a custom insight

From the Insights card, click View all insights, then Create. You can tick one or more of Google's suggested insights and click Create selected, use a suggestion as a template with Review and create, or click Create new under Start from scratch. A custom insight has these parts:

• Evaluation frequency: Hourly, Daily, Weekly or Monthly. Hourly is "available only for web data." Google explains that app events often arrive late (for example when an app is used offline), which would trigger false notifications, so hourly insights for app events are not offered.
• Segment: All Users by default. Click Change to pick a dimension and value, such as one country or one traffic source, and choose whether to include or exclude it.
• Metric and condition: the metric, a condition and a threshold. Google's example is "30-day active users - % decrease more than - 20." If you choose Has anomaly as the condition, you do not enter a value; GA4 decides when the change is unusual.
• Name: what the alert will be called on the dashboard and in the email.
• Notifications: email addresses of people who should receive it.

Then click Create in the upper right. A fixed threshold, such as sessions down by more than 30%, is easy to explain to a client. Has anomaly adapts to the property's normal ups and downs, which suits metrics that swing by day of week.

Email alerts and managing insights

Google says that by default "all users on a property see all triggered custom insights" on the dashboard. Email only goes to the addresses you add. To change an existing one, open View all insights and click Manage to see the property's custom insights. For each, you can turn the Email Notifications switch on or off, or delete it.

Google describes automated insights as notifying you "within the Analytics platform," and lists email only for custom insights. If a change has to reach someone's inbox, set it up as a custom insight.

How anomaly detection works

Both automated insights and the Has anomaly condition rely on anomaly detection. Google's anomaly detection article describes two methods:

• Over time. GA4 applies "a Bayesian state-space time series model" to past data to predict the latest value, with a credible interval around it. If the actual value falls outside that interval, it is flagged. The history used depends on frequency: 2 weeks for hourly, 90 days for daily and 32 weeks for weekly anomalies.
• Across segments at one point in time. GA4 compares many segments and metrics at once using principal components analysis. A segment is flagged if it behaves unusually on any metric and "comprises at least 0.05% of the users on that property." Google says this analysis runs every week.

In practice this means a new property, or a metric with little history, has less to compare against. A daily anomaly is judged against the last 90 days, so a change that has lasted for weeks slowly becomes the new normal.

Limits and permissions

• Number: "up to 50 custom insights per property."
• Role: "You need the Editor or Administrator role to create, edit, and share insights." Our user permissions guide explains the roles.
• Restricted metrics: Google's data restriction article says a user without access to cost or revenue metrics cannot see automated insights based on them, and cannot see custom insights based on them "in the user interface" or "receive them via email." See data restrictions in our permissions guide.

Custom insights vs scheduled report emails

GA4 can also email whole reports on a timetable. Per Google's scheduled reports article, an administrator can schedule "up to 50 standard and custom reports" by email from Share this report > Schedule Email; the Realtime report cannot be scheduled. The difference is simple: a scheduled email arrives every time, while a custom insight arrives only when its condition is met. Many teams use both, a weekly report for routine reading and a few insights for problems. For client-facing summaries we usually build a Looker Studio dashboard instead.

How we set up alerts

This is our own practice, not Google guidance:

• We start with a handful of custom insights, not dozens: the main key event (leads or purchases) and total sessions, each daily, with Has anomaly. Too many alerts get ignored.
• We add a fixed-threshold insight for cases where tracking breaks, such as the key event dropping by close to 100% in a day, because a broken tag matters more than a normal dip.
• Emails go to the person who will act on them, usually the site owner and us, not the whole team.
• When an alert fires, we check the Realtime report and DebugView first to see whether events are still arriving, then look at the site, the tags and any recent changes. Our annotations guide covers noting releases and campaigns so the next alert is easier to explain.

Frequently asked questions

How do I set up alerts in GA4?

Create a custom insight: open View all insights from the Insights card on the Home page, click Create, set the frequency, segment, metric and condition, name it, add the email addresses that should be notified and click Create. You need the Editor or Administrator role.

How many custom insights can a GA4 property have?

Google allows up to 50 custom insights per property. Insights that have been triggered are kept for one year after they are generated.

Can I get hourly alerts for my app in GA4?

No. Hourly evaluation is available only for web data. Google says app events often arrive with a delay, for example when the app is used offline, which would trigger false notifications.

What does Has anomaly mean in a custom insight?

It lets GA4 decide when a change is unusual instead of you entering a threshold. GA4 predicts the expected value from past data, using 2 weeks of history for hourly, 90 days for daily and 32 weeks for weekly checks, and flags values outside the expected range.

Why can't a colleague see an insight I created?

If the insight is based on cost or revenue metrics and their access excludes those metrics, they cannot see it in GA4 or receive it by email. Custom insights only go by email to the addresses added to them.

For more on measurement, see our guides to GA4 basics, key events, the Events report, explorations and monthly website reporting.

Want a website where every enquiry is tracked and easy to analyse? See our website development service and all our services, or email [email protected].