Understanding Data Sampling in Google Analytics 4 (GA4)

Last Updated: September 9, 2022

In this article, I will talk about understanding data sampling in Google Analytics 4 (GA4). I will also cover hit limits, thresholding and cardinality in Google Analytics 4.

In data analysis, sampling is the process of analyzing a subset of data for analysis and reporting based on the similarity detected in the subset and the larger data set. 

For example, if you want to estimate the number of cars parking in a 1000 square meter area where the distribution of car parking was fairly uniform, you could count the number of cars parking in 10 square meters and multiply by 100, or count the cars parking in a 5 square meter and multiply by 200 to get an accurate representation of the entire 1000 square meters. 

In Google Analytics 4, a few reports are always unsampled, and a few are sampled based on the conditions. Let’s understand how sampling happens in GA4 in more detail.

Data sampling in Google Analytics 4 

In Google Analytics 4, reporting is divided into two categories in the ‘Analysis’ tab; standard reports and advanced reports. 

Standard reports are always unsampled in GA4 (based on 100% of data for the selected date range), and advanced reports are sometimes sampled based on the conditions of what data you choose to see. 

The below image shows the standard reporting options in GA4, which are unsampled.

Standard reports in ga4

The next image shows the advanced reporting options in GA4, which are sometimes sampled.

Sometime sample reports

These advanced reports include the following techniques:

technique 1

Unlike in Universal Analytics, the data may be sampled if you apply a secondary dimension or segment to the standard reports. But in the case of GA4, you can apply comparisons, and secondary dimensions, filter your reports, and everything will continue to be unsampled.

If you are viewing an unsampled GA4 report, then you will see a green reporting icon with a checkmark at the top of the report:

green symbol

If you hover your mouse over the green reporting icon, you will see the following message “This report is based on 100.0% of available data.”

100 percent data

If you are viewing a sampled GA4 report, then you will see a yellow reporting icon with a % symbol at the top of the report:

Yello symbol

If you hover your mouse over the yellow reporting icon, you will see the following message “This report is based on XX% of available data.” (In our case, XX represents 95.28%).

sampled data

Sampling differences in Google Analytics 4 Vs Universal Analytics

In Universal Analytics, default reports (standard reports) are not subject to sampling. But if you apply ad-hoc queries to your data (like secondary dimensions or segments), they are subject to the below general sampling thresholds.

  • Standard Analytics: 500k sessions at the property level for the date range you are using
  • Analytics 360: 100M sessions at the view level for the date range you are using

If you want to know more about sampling in Universal Analytics, you can read it here: Understanding Data Sampling in Google Analytics

In the case of Google Analytics 4, the default reports (standard reports) are always unsampled. You can apply comparisons and custom parameters to your report, and all the reports will continue to be unsampled. 

The advanced report in the ‘Analysis’ tab may sometimes be sampled. In general, sampling occurs in advanced reporting when the data exceeds 10 million in counts, and the report you are creating is not a replica (similar) to the standard report.  

Hit limits in Google Analytics 4

In the case of Universal Analytics (standard), there is a hit limit of 10 million per month per account. However, Google Analytics 4 is a free tool and has no hit limits. I have searched a lot about this, but it is not mentioned anywhere in the documentation. This makes it a more premium analytics tool at no cost.

Thresholding in Google Analytics 4

In Google Analytics 4, thresholds are applied to prevent anyone viewing a report from inferring the demographics or interests of individual users to the website. 

When a report contains age, gender, or interest categories (e.g. as a primary or secondary dimension, a data comparison, or a segment), a threshold may be applied, and some data may be kept hidden (unknown) from the report. 

Google defines these thresholds, and you cannot adjust them. However, if a threshold has been applied to a report, you will see unknown values in the report. These values are replaced by “unknown” to keep user identity and basic information hidden.

thresholding

Cardinality in Google Analytics 4

Each report in Google Analytics 4 has dimensions assigned to it, and each dimension has several values that can be assigned to it. For example, the gender dimension has three potential values (male, female or other), so that dimension’s cardinality is three. 

The total number of unique values for a dimension is known as its cardinality. 

Dimensions with a large number of possible values are known as high-cardinality dimensions. For example, the page dimension has different values for every URL on your website. 

If a report contains high-cardinality dimensions, it may get affected by Google Analytics system limits (Google-defined), resulting in the creation of rolled-up (other) entries in the report. 

Cardinality may occur in standard reports as well as advanced reports in the ‘Analysis’ tab. 

There is no such definition available from Google on when cardinality appears (limit), but in general, this may occur if you have more than 25,000 to 30,000 unique values for a dimension in the selected date range.

cardinality

Summary

GA4 will always show you unsampled reports for standard reports, and only in the case of advanced reporting options in the ‘Analysis’ tab (cohort analysis, exploration, segment overlap, funnel analysis, path analysis, and user explorer) might they be sampled. 

Related Article: Google Analytics Sampling Tutorial

#1 Google Analytics 4 Intro

  1. What is GA4 (Google Analytics 4) – The Apps + Web Property?
  2. Key Benefits of Using Google Analytics 4 (GA4)
  3. Setup GA4 – Upgrade to GA4 – Implementation Guide
  4. Google Analytics 4 (GA4) vs Universal Analytics – What is the Difference?
  5. GA4 vs GA4 360 – Pricing, Limits, Billing and More
  6. Google Analytics 4 Training & Tutorial with FREE GA4 ebook

#2 Google Analytics 4 Property

  1. Google Analytics Account Hierarchy (Structure Explained)
  2. Understanding Google Analytics Measurement ID (GA4)
  3. Google Signals GA4 – See Demographics (Gender, Age) in Google Analytics 4
  4. Using the GA4 (Google Analytics 4) Test Property
  5. Google Analytics 4 Sub Properties Tutorial
  6. Roll up Property in Google Analytics 4 (GA4) – Tutorial

#3 Google Analytics 4 Integrations

  1. How to connect GA4 (Google Analytics 4) with Google Data Studio
  2. How to link GA4 (Google Analytics 4) with Google Ads
  3. How to link Google Search Console to Google Analytics 4 (GA4)
  4. How to Install Google Analytics 4 on Shopify
  5. GA4 Firebase Integration – Correctly Add App Data Streams to GA4 Property

#4 Google Analytics 4 Events

  1. GA4 (Google Analytics 4) Event Tracking Setup Tutorial
  2. Understanding Event Parameters in Google Analytics 4 (GA4)
  3. Recommended Events in Google Analytics 4 (GA4)
  4. Enhanced Measurement Events in Google Analytics 4 (GA4)
  5. Automatically Collected Events in Google Analytics 4 (GA4)
  6. How to Set Up GA4 Custom Events via Google Tag Manager
  7. Events Report in Google Analytics 4 (GA4)
  8. How to Rename Events in Google Analytics 4 (GA4)
  9. How to Use Google Analytics 4 Event Builder

#5 Google Analytics 4 Conversions

  1. Google Analytics 4 Conversion Tracking Guide – GA4 Goals
  2. How to Import Conversions from GA4 Property to Your Google Ads account
  3. GA4 Conversion Rate – How to find it and use it

#6 Google Analytics 4 Dimensions

  1. GA4 (Google Analytics 4) Dimensions Tutorial
  2. GA4 (Google Analytics 4) Custom Dimensions Tutorial
  3. GA4 User Properties (User Scoped Custom Dimensions) – Tutorial
  4. Event Scoped Custom Dimensions in GA4 – Tutorial

#7 Google Analytics 4 Metrics

  1. GA4 (Google Analytics 4) Metrics Tutorial with Free Google Analytics 4 Ebook
  2. GA4 (Google Analytics 4) Custom Metrics Tutorial
  3. What are Predictive Metrics in Google Analytics 4 (GA4)

#8 Google Analytics 4 Ecommerce

  1. GA4 (Google Analytics 4) Ecommerce Tracking via GTM – Tutorial

#9 Google Analytics 4 Specialized Tracking

  1. GA4 (Google Analytics 4) Enhanced Measurement Tracking Tutorial
  2. Cross Domain Tracking in GA4 (Google Analytics 4) Setup Guide
  3. GA4 Site Search – Tracking Site Search in Google Analytics 4
  4. GA4 (Google Analytics 4) Scroll Tracking Tutorial
  5. Self-referral Google Analytics 4 – Referral exclusion GA4
  6. GA4 (Google Analytics 4) Data Import Tutorial
  7. Google Analytics 4 Content Grouping – Create Content Groups in GA4
  8. How to Track Single Page Apps in Google Analytics 4 (GA4)
  9. utm_source, utm_medium, utm_campaign Parameters – GA4 (Google Analytics 4)

#10 Google Analytics 4 filters

  1. GA4 filters – Understanding Data Filters in Google Analytics 4
  2. How to Create and Test Filters in Google Analytics 4 (GA4)?
  3. Exclude Internal Traffic in GA4 (Google Analytics 4) via IP Filter

#11 Google Analytics 4 Explorations

  1. Free Form Report in GA4 (Google Analytics 4) – Exploration Report
  2. How to Use the User Lifetime Report in Google Analytics 4 (GA4)
  3. How to Use Path Exploration Report in GA4 (Google Analytics 4) – Path Analysis
  4. How to Use Segment Overlap Report in Google Analytics 4 (GA4)
  5. How to Use the Funnel Exploration Report in GA4 (Google Analytics 4) – Funnel Analysis
  6. Cohort Exploration Report in Google Analytics 4 (GA4)
  7. How to Create Landing Pages Report in GA4 (Google Analytics 4)
  8. How to Create Google Ads report in GA4 (Google Analytics 4)
  9. How to Segment GA4 Data by Data Stream
  10. Organic Search Traffic Analysis in GA4 – Complete Guide

#12 Google Analytics 4 Advanced

  1. Understanding Google Analytics 4 Sessions
  2. GA4 (Google Analytics 4) Measurement Protocol Tutorial
  3. How to Build Comparisons (Advanced Segments) in Google Analytics 4 (GA4)
  4. Understanding Automated Insights in Google Analytics 4 (GA4)
  5. Understanding Channel Groupings in Google Analytics 4 (GA4)
  6. Understanding Data Sampling in Google Analytics 4 (GA4)

#13 Google Analytics 4 Reports

  1. How to Create Custom Insights in Google Analytics 4 (GA4)
  2. How to Use Debug View Report in Google Analytics 4 (GA4)

#14 Google Analytics 4 Attribution

  1. Guide to Attribution Models in GA4 (Google Analytics 4)
  2. How to Change Attribution Models in GA4 (Google Analytics 4)?
  3. GA4 (Google Analytics 4) Conversion Paths Report in Attribution
  4. GA4 (Google Analytics 4) Model Comparison Report in Attribution
  5. Advertising Snapshot in GA4 (Google Analytics 4) Attribution
  6. GA4 Attribution Modelling Tutorial

#15 Google Analytics 4 Audiences

  1. GA4 Audiences – Creating Custom Audience in Google Analytics 4
  2. How to Create a Remarketing Audience in Google Analytics 4 (GA4)
  3. Understanding Audience Triggers in Google Analytics 4 (GA4)
  4. Google Analytics 4 (GA4) Predictive Audiences – Tutorial

#16 Google Analytics 4 BigQuery

  1. GA4 BigQuery – Connect Google Analytics 4 with BigQuery
  2. BigQuery GA4 Schema – Send Custom GA4 Data to BigQuery
  3. How to Backfill GA4 Data in BigQuery
  4. How to Connect and Export Data from GA

Frequently Asked Questions about Understanding Data Sampling in Google Analytics 4 (GA4)

What is data sampling?

In data analysis, sampling is the process of analyzing a subset of data for analysis and reporting based on the similarity detected in the subset and the larger data set. 

Are all reports in GA4 sampled?

Standard reports are always sampled in GA4 (based on 100% of data for the selected date range), and advanced reports are sometimes sampled based on the conditions of what data you choose to see. 

What is thresholding in GA4?

When a report contains age, gender, or interest categories (e.g. as a primary or secondary dimension, a data comparison, or a segment), a threshold may be applied, and some data may be kept hidden (unknown) from the report. 

Google defines these thresholds, and you cannot adjust them. However, if a threshold has been applied to a report, you will see unknown values in the report. These values are replaced by “unknown” to keep user identity and basic information hidden.

What is cardinality in GA4?

The total number of unique values for a dimension is known as its cardinality. For example, the gender dimension has three potential values (male, female or other), so that dimension’s cardinality is three. 

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