Web Analytics FAQ

GA4 Basics

What is GA4?

GA4 (Google Analytics 4) is the current version of Google Analytics. It replaced Universal Analytics in July 2023. GA4 uses an event-based data model where every interaction - page views, clicks, scrolls, purchases - is recorded as an event with parameters. This approach gives you more flexibility in tracking user behavior than the old session-and-pageview model.

How is GA4 different from Universal Analytics?

Universal Analytics tracked pageviews and sessions. GA4 tracks events. In UA, you had separate hit types for pageviews, events, transactions, and social interactions. In GA4, everything is an event. GA4 also uses a different user identity model, supports cross-platform tracking (web + app), and calculates metrics like session duration and engagement rate differently.

The migration from Universal Analytics to GA4 caught many site owners off guard. Analytics expert Krista Seiden urged the community to make the switch well before the July 2023 deadline.

What are events in GA4?

Events are the foundation of GA4 data collection. Every user interaction is an event: page_view, scroll, click, purchase, file_download, and so on. Each event can carry parameters that describe it further - for example, a page_view event includes page_location and page_title. GA4 collects some events automatically, others through enhanced measurement, and you can create custom events for anything else.

What is an engaged session?

An engaged session in GA4 is any session that lasts longer than 10 seconds, includes a key event (conversion), or has at least 2 page or screen views. This metric replaced the old concept of non-bounced sessions. GA4 uses engaged sessions as the basis for calculating engagement rate, which is the percentage of sessions that qualify as engaged.

What replaced bounce rate in GA4?

GA4 introduced engagement rate as the primary metric instead of bounce rate. Engagement rate is the percentage of engaged sessions (sessions lasting 10+ seconds, having 2+ page views, or including a key event). Bounce rate is still available in GA4 but is now simply the inverse: bounce rate = 100% minus engagement rate. The shift reflects a more meaningful way to measure whether visitors found value on your site.

The disappearance of bounce rate in GA4 surprised many analysts. Krista Seiden explained why engagement rate is a better fit for modern analytics.

How do I set up GA4?

Go to analytics.google.com and create a new GA4 property. Add a web data stream for your domain, then install the measurement tag on your site - either by pasting the gtag.js snippet into your HTML head or by deploying it through Google Tag Manager. Enhanced measurement is enabled by default and covers page views, scrolls, outbound clicks, site search, video engagement, and file downloads without any extra configuration.

What is the data retention period in GA4?

GA4 retains event-level data for either 2 months or 14 months, depending on your settings. Standard reports use aggregated data that is not affected by this limit. The data retention setting only impacts Explorations and other reports that query raw event data. If you need longer retention, export your data to BigQuery where you control storage duration. MeasureBoard stores up to 18 months of daily analytics data regardless of your GA4 retention setting. Read our guide to reading Google Analytics for tips on making the most of your data.

What are GA4 explorations?

Explorations are GA4's advanced analysis tools that let you build custom reports beyond the standard ones. There are several templates: Free Form (pivot tables), Funnel Exploration, Path Exploration, Segment Overlap, Cohort Exploration, and User Lifetime. They offer more flexibility than standard reports but are subject to data retention limits and data sampling thresholds.

Tracking & Implementation

What is Google Tag Manager?

Google Tag Manager (GTM) is a free tool that lets you add and manage tracking codes on your website without editing source code directly. Instead of hardcoding scripts, you create tags in GTM's web interface and define triggers for when they fire. GTM supports Google Analytics, Facebook Pixel, custom HTML, and hundreds of other tag templates. It makes deployment faster and reduces the risk of breaking your site with bad tracking code.

What is server-side tagging?

Server-side tagging moves your tracking logic from the user's browser to a server you control. Instead of the browser sending data directly to Google Analytics, Facebook, and other platforms, it sends one request to your server container, which then forwards data to each destination. Benefits include better data quality, reduced page load times, and more control over what data leaves your site. The tradeoff is added infrastructure cost and complexity.

Simo Ahava, one of the foremost experts on Google Tag Manager, announced the launch of server-side tagging when it entered public beta.

How do I track conversions in GA4?

In GA4, conversions are called key events. Mark any event as a key event in Admin > Events by toggling the switch next to it. Common key events include purchase, sign_up, and generate_lead. You can also create custom events based on conditions - for example, a page_view event where page_location contains /thank-you. GA4 counts one key event per session by default, though you can change this to count every occurrence.

What are UTM parameters?

UTM parameters are tags appended to URLs that tell analytics tools where traffic came from. The five standard parameters are utm_source (e.g., google), utm_medium (e.g., cpc), utm_campaign (e.g., spring_sale), utm_term (keyword), and utm_content (ad variant). GA4 reads these automatically and populates the Source, Medium, and Campaign dimensions. Use them on every link in emails, ads, and social posts to get accurate attribution data.

What is a data layer?

A data layer is a JavaScript object on your page that stores structured information for Google Tag Manager and other tracking tools to read. Instead of scraping data from the page's HTML (fragile and unreliable), your website pushes variables like product IDs, prices, and user types into the data layer. GTM triggers can then access this data cleanly. E-commerce tracking, in particular, relies heavily on a well-structured data layer.

How do I track e-commerce in GA4?

GA4 e-commerce tracking requires sending specific events with defined parameters: view_item, add_to_cart, begin_checkout, and purchase. Each event includes an items array with product details (id, name, price, quantity). You can implement this through gtag.js or Google Tag Manager with a data layer. Once set up, GA4 populates the Monetization reports with revenue, transactions, average order value, and product performance data.

What is consent mode?

Consent mode is Google's framework for adjusting how tags behave based on a user's cookie consent choices. When a user declines analytics cookies, consent mode sends cookieless pings to GA4 instead of full tracking. Google then uses machine learning to model the missing data, filling gaps in your reports. Consent mode v2, required for EU users since March 2024, adds two new signals: ad_user_data and ad_personalization.

How do I debug tracking issues?

GA4 has a built-in DebugView (Admin > DebugView) that shows events arriving in real time from devices with debug mode enabled. For GTM, use the Preview mode to test which tags fire on each page. The Chrome extension Tag Assistant helps verify your GA4 installation. Check the real-time report in GA4 to confirm data is flowing. Common issues include duplicate tags, misconfigured filters, and consent mode blocking data collection.

Metrics & Dimensions

What is the difference between a session and a user?

A user is a unique visitor identified by a cookie or device ID. A session is a single visit - it starts when the user arrives and ends after 30 minutes of inactivity. One user can generate many sessions over time. If someone visits your site Monday morning and again Wednesday evening, that counts as one user and two sessions. The user count tells you audience size; session count tells you total visit volume. Our Google Analytics guide walks through how to interpret these metrics in practice.

What is engagement rate?

Engagement rate is the percentage of sessions that were engaged - meaning they lasted longer than 10 seconds, included a key event, or had 2 or more page views. It replaced bounce rate as GA4's default quality metric. A 60% engagement rate means 60 out of 100 sessions had meaningful interaction. Compare engagement rates across pages and traffic sources to identify what content and channels bring the most valuable visitors.

What are active users?

Active users is GA4's primary user metric. A user counts as active when they have an engaged session or when GA4 collects certain events (first_visit, engagement_time_msec). In most standard reports, 'Users' means active users, not total users. This is different from Universal Analytics, where users included everyone who visited regardless of engagement. The distinction means GA4 user counts may be lower than what you saw in UA.

How is average session duration calculated in GA4?

GA4 calculates average session duration as the total time users spent on your site divided by the number of sessions. Unlike Universal Analytics, GA4 can measure time on the last page of a session because it uses the engagement_time_msec event parameter. This means GA4 session durations are generally more accurate. A session with one page view and 45 seconds of active time will report 45 seconds, not zero as UA would have.

What are custom dimensions?

Custom dimensions let you collect and analyze data that GA4 does not track by default. Examples include user role (free vs. paid), content type (blog vs. product), or A/B test variant. You register custom dimensions in GA4 Admin > Custom Definitions, then send the corresponding event parameter or user property from your tracking code. GA4 allows up to 50 custom event-scoped dimensions and 25 user-scoped dimensions.

What is a key event?

Key event is GA4's term for what most people call a conversion. Any event you mark as a key event in GA4 Admin gets tracked as a conversion action. When a user completes a key event, GA4 attributes it to the traffic source that brought them in. Common key events include purchase, sign_up, form_submit, and phone_call_click. The name change from 'conversion' to 'key event' happened in 2024 to distinguish GA4 conversions from Google Ads conversions.

What are cohort reports?

Cohort reports group users by a shared characteristic - usually their acquisition date - and track their behavior over time. For example, you can compare users acquired in January vs. February to see which group has better retention. GA4's Cohort Exploration lets you define cohorts by first visit date and measure retention, engagement, or revenue over daily, weekly, or monthly intervals. This is useful for evaluating whether changes to your site improve long-term user behavior.

What is user lifetime value?

User Lifetime Value (LTV) in GA4 measures the total revenue and engagement a user generates from their first visit through their entire relationship with your site. GA4's User Lifetime exploration shows cumulative metrics like lifetime revenue, lifetime sessions, and lifetime engagement time per user. For e-commerce sites, LTV helps you decide how much you can afford to spend acquiring a customer. For content sites, it reveals how loyal your audience actually is.

Attribution & Conversion

What is attribution modeling?

Attribution modeling determines which marketing touchpoints get credit for a conversion. If a user finds your site through organic search, later clicks a Facebook ad, and finally converts after an email - which channel gets credit? Different attribution models answer this question differently. GA4 uses data-driven attribution by default, which uses machine learning to distribute credit based on how each touchpoint actually influenced the conversion.

What is the difference between first-click and last-click attribution?

First-click attribution gives 100% of the conversion credit to the first touchpoint that introduced the user to your site. Last-click attribution gives 100% to the final touchpoint before conversion. First-click favors awareness channels (social, display); last-click favors closing channels (brand search, email). Neither tells the full story, which is why GA4 defaults to data-driven attribution that distributes credit across multiple touchpoints.

What is data-driven attribution?

Data-driven attribution (DDA) is GA4's default model. It uses machine learning to analyze all the conversion paths on your site and assign fractional credit to each touchpoint based on how much it actually contributed to conversions. If your data shows that users who see a display ad before searching your brand are 3x more likely to convert, DDA gives the display ad proportional credit. DDA requires enough conversion data to build a reliable model - Google recommends at least 400 conversions over 28 days.

How do I set up conversion tracking?

In GA4, go to Admin > Events, find the event you want to track as a conversion, and toggle the 'Mark as key event' switch. If the event does not exist yet, create it first - either through enhanced measurement settings, the GA4 interface (create event), or by sending it from your tracking code via gtag.js or GTM. Test the conversion in DebugView before relying on it for campaign optimization.

What is cross-domain tracking?

Cross-domain tracking ensures that a user who navigates between two or more domains you own (e.g., shop.example.com and www.example.com) is counted as a single user with a continuous session. Without it, GA4 would treat the domain change as a new session from a referral source. Set it up in GA4 Admin > Data Streams > Configure Tag Settings > Configure Your Domains. GA4 handles this by appending a linker parameter to cross-domain links.

What is a conversion funnel?

A conversion funnel maps the steps users take from first interaction to final conversion - for example, homepage > product page > add to cart > checkout > purchase. GA4's Funnel Exploration report shows how many users complete each step and where they drop off. High drop-off between specific steps reveals friction points. An e-commerce site losing 70% of users between cart and checkout has a clear optimization target.

Reporting & Analysis

How do I create custom reports in GA4?

GA4 offers two paths for custom reporting. Standard custom reports are built in Reports > Library where you can create new detail or overview reports with chosen dimensions and metrics. For more advanced analysis, use Explorations - they support free-form tables, funnels, path analysis, and cohorts. You can also connect GA4 to Looker Studio for fully customizable dashboards that combine data from multiple sources.

What is Looker Studio?

Looker Studio (formerly Google Data Studio) is Google's free data visualization and reporting tool. It connects directly to GA4, Search Console, BigQuery, Google Ads, and hundreds of other data sources through connectors. You build interactive dashboards with charts, tables, and filters that update automatically. It is the standard tool for creating client-facing or executive analytics dashboards when GA4's built-in reports are not enough.

How do I compare date ranges in GA4?

In any GA4 report, click the date picker in the top right and enable the comparison toggle. You can compare to the previous period, same period last year, or a custom date range. Comparison data appears as delta percentages next to each metric. MeasureBoard builds this comparison into every report automatically - showing month-over-month and year-over-year changes so you can spot trends without manual date selection. MeasureBoard's Analytics Reporting includes automatic period comparisons in every report.

What are segments in GA4?

Segments are subsets of your data defined by conditions you set. In GA4 Explorations, you can create user segments (users who match criteria), session segments (sessions matching criteria), and event segments (specific events matching criteria). For example, a segment of 'users from organic search who viewed 3+ pages' lets you analyze the behavior of your most engaged organic visitors separately from the rest of your traffic.

How do I find my traffic sources in GA4?

Navigate to Reports > Acquisition > Traffic Acquisition in GA4. This report breaks down sessions by channel group, source, and medium. The default channel grouping categorizes traffic into Organic Search, Paid Search, Direct traffic, Referral, Social, Email, and others. For more detail, add a secondary dimension like Source/Medium to see exactly which websites or campaigns drive your traffic. MeasureBoard surfaces this data automatically in your dashboard with trend charts and channel breakdowns.

What is real-time reporting?

The Realtime report in GA4 shows activity on your site in the last 30 minutes. It displays active users, their geographic location, traffic sources, pages being viewed, and events being triggered - all updating live. Realtime is most useful for verifying that tracking is working, monitoring the impact of a just-published social post or email campaign, and spotting unusual traffic spikes as they happen.

How do I export GA4 data to BigQuery?

GA4 has a native BigQuery export that streams event-level data to a Google Cloud BigQuery project at no additional GA4 cost (standard BigQuery storage and query costs apply). Enable it in GA4 Admin > BigQuery Links. Once configured, GA4 exports every event with all parameters into daily tables. This gives you raw, unsampled data with SQL access - useful for custom analysis that exceeds what the GA4 interface can handle.

What are anomaly detection alerts in GA4?

GA4's custom insights feature lets you create alerts that trigger when a metric crosses a threshold you define. For example, alert when daily sessions drop by more than 30% compared to the previous week, or when a specific conversion rate falls below a target. GA4 also runs automated anomaly detection that flags unusual changes in your data. Both types appear in the Insights section of GA4 and can be emailed to you.

Privacy & Compliance

What is cookie consent?

Cookie consent is the legal requirement to inform users about cookies your site uses and obtain their permission before setting non-essential ones. The EU's GDPR and ePrivacy Directive require explicit opt-in consent for analytics and advertising cookies. A consent banner (CMP) presents the choice. When users decline, your analytics data has gaps - which is why Google built Consent Mode to model that missing data.

How does GDPR affect analytics?

GDPR requires websites serving EU users to get explicit consent before collecting personal data through analytics tools. IP addresses, device identifiers, and cookies all qualify as personal data. You must display a consent banner, honor opt-out choices, and document your data processing. GA4 offers IP anonymization by default and integrates with consent management platforms. If a significant portion of your audience is in the EU, expect 20-40% of users to decline tracking.

What is cookieless tracking?

Cookieless tracking refers to analytics methods that work without storing cookies on the user's device. Approaches include server-side tracking, first-party data collection, fingerprinting (controversial and increasingly blocked), and Google's modeling features in Consent Mode. As browsers phase out third-party cookies and privacy regulations tighten, cookieless tracking is becoming more relevant. GA4's modeling fills gaps when cookies are unavailable, but the accuracy depends on having enough consented data to train the model.

What is data sampling in GA4?

Data sampling occurs when GA4 analyzes a subset of your data instead of the full dataset, then extrapolates the results. In standard reports, GA4 uses pre-aggregated data that is not sampled. Sampling kicks in when you use Explorations, apply segments, or run ad-hoc queries on large datasets. A green checkmark icon means unsampled; a yellow shield means sampled. To avoid sampling, narrow your date range, simplify your query, or export to BigQuery for unsampled analysis.

How do I anonymize IP addresses?

GA4 anonymizes IP addresses by default - you do not need to configure anything. Google strips the last octet of IPv4 addresses and the last 80 bits of IPv6 addresses before storing them. This was an opt-in setting in Universal Analytics but is automatic in GA4. Note that IP anonymization alone does not make you GDPR-compliant; you still need consent for setting cookies and processing other user identifiers.

What is consent mode v2?

Consent mode v2 is an update Google rolled out in 2024 that adds two new consent signals: ad_user_data (whether user data can be sent to Google for ad purposes) and ad_personalization (whether ads can be personalized). It is required for serving personalized ads to users in the European Economic Area. If you use Google Ads and target EU users, implementing consent mode v2 through your consent management platform is mandatory to maintain ad campaign functionality.

Advanced Topics

What is predictive analytics in GA4?

GA4 includes machine learning models that generate predictive metrics: purchase probability (likelihood a user will buy in the next 7 days), churn probability (likelihood a user will not return in 7 days), and predicted revenue. These metrics require minimum thresholds of data quality and volume. You can build predictive audiences from them - for example, targeting users with high purchase probability in Google Ads remarketing campaigns.

How do I use audiences for remarketing?

In GA4 Admin > Audiences, create an audience based on conditions like users who visited a product page but did not purchase, or users who have been active in the last 7 days. When you link GA4 to Google Ads, these audiences automatically sync for remarketing campaigns. You can refine audiences with event conditions, user properties, and time-based criteria. GA4 populates audiences going forward from creation, not retroactively.

What is measurement protocol?

The GA4 Measurement Protocol is an HTTP API that lets you send events to GA4 from any internet-connected device - servers, IoT devices, kiosks, or offline systems. You send a POST request with your measurement ID, API secret, and event payload. Common use cases include tracking server-side events (refunds, subscription renewals), offline conversions, and CRM actions. Events sent via Measurement Protocol appear alongside regular GA4 data.

What are calculated metrics?

Calculated metrics in GA4 let you create new metrics from mathematical operations on existing ones. For example, revenue per session (totalRevenue / sessions) or content engagement score (eventCount / sessions). You define them in GA4 Admin > Custom Definitions > Calculated Metrics. They show up in standard reports and can be used alongside built-in metrics. This feature saves you from exporting data to a spreadsheet for basic calculations.

How do I integrate GA4 with Google Ads?

Link your GA4 property to Google Ads in GA4 Admin > Google Ads Links. Once linked, GA4 key events automatically import into Google Ads as conversions, and Google Ads campaign data appears in GA4 reports. This two-way integration lets you see which ad campaigns drive the most valuable users and optimize bidding based on GA4 conversion data rather than just click-through rates.

What is enhanced measurement?

Enhanced measurement is a GA4 feature that automatically tracks common interactions without any code changes: page views, scrolls (90% depth), outbound link clicks, site search, video engagement (YouTube embeds), and file downloads. It is enabled by default when you create a data stream. You can toggle individual events on or off in Admin > Data Streams > Enhanced Measurement. For most sites, enhanced measurement covers 80% of basic tracking needs out of the box.

Analytics architect Simo Ahava has been vocal about GA4's design decisions, particularly around how the platform handles event propagation and session cookies.