Google Analytics (GA4) Interview Questions and Answers

GA4 is Google’s current web and app analytics platform. It measures how people find and use a website or app, using an event-based data model. It replaced Universal Analytics, which stopped processing data on 1 July 2023.

A Google tag (gtag.js) or Google Tag Manager on the website — or the Firebase SDK in an app — sends events to Google Analytics whenever users interact. GA4 processes those events into reports.

GA4 uses events instead of sessions and hits, combines web and app data in one property, replaces goals with key events, replaces views with data streams, uses engagement rate alongside bounce rate, and offers the Explorations workspace and free BigQuery export.

A data stream is a source of data flowing into a GA4 property — a website (web stream) or an iOS or Android app. One property can have several streams.

Organisation (optional) → Account → Property → Data streams. Universal Analytics views no longer exist; filters and settings are applied at the property level.

A user is a unique person (identified by device, User-ID or Google signals), and a session is a group of interactions within a time frame. One user can have many sessions.

Dimensions describe data (for example, source, page path, country). Metrics are numbers (for example, users, sessions, engagement rate, revenue).

Create a GA4 property, add a web data stream, then install the Google tag with the Measurement ID (G-XXXXXXX) directly on the site or through Google Tag Manager. Verify data in the Realtime report or DebugView.

Enhanced measurement automatically tracks common interactions without extra code: page views, scrolls (90% depth), outbound clicks, site search, video engagement on embedded YouTube videos, file downloads and form interactions.

Automatically collected events, enhanced measurement events, recommended events (Google’s suggested names such as purchase or sign_up) and custom events that you define.

Enable site search in enhanced measurement and add the query parameter your site uses (for example q or s). Searches are recorded as the view_search_results event.

Define internal traffic rules with your office IP addresses in the data stream settings, then activate the Internal traffic data filter at property level. Test it first in “Testing” mode.

In the web data stream, open Configure tag settings → Configure your domains and list all domains. GA4 then adds a linker parameter so users are recognised as they move between your domains.

Add an iOS or Android data stream and integrate the Firebase SDK in the app. App and web data then appear together in the same property.

DebugView shows events from a debug device in real time, so you can check that events and parameters are firing correctly before publishing changes.

GA4 collects, processes and reports data. Google Tag Manager is a tag management system that deploys tags — including GA4 — and triggers without editing website code.

Every interaction is an event — a page view, scroll, click, form submission or purchase. Each event can carry parameters with extra details, such as page_location or value.

A key event is an event you mark as important for your business, such as generate_lead or purchase. Google renamed GA4 “conversions” to “key events” in 2024; “conversions” now refers to key events imported into Google Ads.

Use enhanced measurement’s form interactions, or more reliably send a custom event (for example generate_lead) from Google Tag Manager when the form succeeds or the thank-you page loads, and mark it as a key event.

Outbound clicks are tracked automatically by enhanced measurement. For specific buttons, create a click trigger in Google Tag Manager that sends a GA4 event with useful parameters.

Embedded YouTube videos are tracked automatically (video_start, video_progress, video_complete) through enhanced measurement. Other players need custom events through Google Tag Manager.

Send a custom event (or use the page title) when the 404 template loads, including the page path and referrer as parameters, then report on it to find broken links.

Send the recommended e-commerce events — view_item, add_to_cart, begin_checkout, purchase — with an items array, transaction ID, value and currency, usually through the data layer and Google Tag Manager.

They let you report on your own event parameters or user properties. You register the parameter in Admin → Custom definitions before it appears in reports.

Use Data Import to upload CSV data (cost, user or offline event data), or send server-side events with the Measurement Protocol.

An engaged session lasts more than 10 seconds, has a key event or has two or more page views. Engagement rate is the percentage of engaged sessions; bounce rate in GA4 is the opposite — the percentage of sessions that were not engaged.

It shows activity from the last 30 minutes — active users, traffic sources, pages, events and key events — useful for checking tracking and live campaigns.

Standard reports give ready-made summaries in the Reports section. Explorations are flexible analysis tools — free form, funnel, path, segment overlap, cohort and user lifetime — for deeper questions.

A funnel exploration shows how users move through the steps you define (for example product view → add to cart → checkout → purchase) and where they drop off.

A path exploration visualises the sequence of pages or events users follow, forwards from a starting point or backwards from an end point — GA4’s replacement for the old Behaviour Flow report.

It groups users who share a characteristic, such as their first visit week, and shows how their retention or behaviour changes over time.

Segments are subsets of data you apply inside Explorations without changing collected data. Data filters at property level (for example internal or developer traffic) permanently exclude data from processing.

Use the User explorer technique in Explorations, which shows the event stream for an individual user or app instance.

Use Reports → Engagement → Pages and screens for views, users, average engagement time, events and key events by page path or title.

Filter traffic acquisition by the Organic Search channel, analyse landing pages and key events, and link Google Search Console to see queries, impressions and average position in GA4.

Search Console shows how your site performs in Google Search before the click — queries, impressions, rankings, indexing. GA4 shows what users do after they arrive on your site.

Customise the GA4 Reports library or connect GA4 to Looker Studio for shareable dashboards that combine several data sources.

Tags added to a URL — utm_source, utm_medium, utm_campaign, utm_term, utm_content and utm_id — that tell GA4 where a visit came from. Use them on email, social and partner links.

Add consistent UTM parameters to every link and analyse the results in Traffic acquisition by session source/medium and session campaign.

With Google Ads linked and auto-tagging on, Google Ads adds a gclid parameter to ad clicks, so GA4 records campaign, ad group and keyword data without manual UTMs.

Data-driven attribution (the default) and last-click models (paid and organic last click, and Google paid channels last click). First click, linear, time decay and position-based were removed in 2023.

User acquisition shows the channel that first brought a new user (first user source). Traffic acquisition shows the source of each session.

The Advertising section shows key events by channel and the conversion paths users take across touchpoints — GA4’s replacement for the old Multi-Channel Funnels reports.

In Admin → Product links → Google Ads links, link the Ads account, then import GA4 key events into Google Ads and share audiences for remarketing.

Groups of users defined by conditions — for example cart abandoners in the last 7 days — used for analysis and shared with Google Ads for remarketing. Predictive audiences use GA4’s machine-learning predictions.

User-ID lets you send your own ID for signed-in users, so GA4 can connect their activity across devices and sessions. Never send personally identifiable information such as email addresses.

GA4 can export raw, event-level data to BigQuery free of charge (within limits), allowing SQL analysis, data blending and long-term storage.

Machine-learning metrics such as purchase probability, churn probability and predicted revenue, available when a property meets the data thresholds.

Event-level data retention for Explorations can be set to 2 months or 14 months on standard properties (longer on GA4 360). Standard aggregated reports are not affected.

Consent Mode adjusts how Google tags behave based on visitors’ cookie consent choices. With Consent Mode v2 and behavioural modelling, GA4 can estimate data for users who decline cookies while respecting privacy rules such as GDPR and India’s DPDP Act.

Thresholds hide rows with small user counts to protect privacy (often when Google signals is on). Sampling can occur in Explorations on large data sets; standard reports are unsampled.