Implementing Google Tag Manager – Why It’s More Than Just Installing a Module

Google Tag Manager (GTM) is a powerful tool that significantly simplifies tag management on a website. In theory, its implementation is simple: just install the appropriate module for your CMS or paste a code snippet into the website. However, in practice, this approach may not be sufficient, especially for advanced applications like online stores. The key aspect of successful GTM implementation is understanding and correctly utilizing the data layer (DataLayer).

In this article, we will explain why GTM is more than just installation and show how to properly configure the DataLayer to maximize the benefits of this tool.

Why a simple module installation is not enough?

There are many modules available on the market for popular content management systems (CMS), such as WordPress, Magento, or PrestaShop, that offer easy integration with Google Tag Manager. In theory, these modules allow for quick GTM deployment by automatically inserting the code into the website.

However, a simple module installation does not always guarantee that the tool will function correctly in every situation. For example, in online stores where monitoring user behavior (such as adding products to the cart, placing orders, etc.) is crucial, these modules often do not account for all the necessary parameters. It often happens that GTM integration is limited to basic functionalities like tracking page visits or conversions, without properly passing detailed data about transactions and user actions.

What is DataLayer and why is it important?

DataLayer is a special data layer that acts as an intermediary between the website and Google Tag Manager. It allows detailed information about events, products, users, and transactions to be passed to GTM, which can then send this data to analytics tools such as Google Analytics or Google Ads.

DataLayer plays a crucial role in advanced GTM implementations because it enables precise monitoring of user actions and the transmission of detailed information about interactions on the website. For online stores, DataLayer can contain data about:

• Products viewed by the user
• Products added to the cart
• Completed orders (including information like order ID, value, product list)
• Steps of the purchase process (e.g., initiating checkout, selecting a payment method, etc.)

This allows marketers to not only monitor website traffic but also analyze specific stages of the purchasing process, identify problems, and optimize advertising campaigns.

Common issues with DataLayer implementation in online stores

Many available GTM modules for CMS and e-commerce platforms provide only basic information to the DataLayer. In practice, they lack detailed data that is essential for effectively tracking user actions in online stores. Here are some common issues:

1. Incomplete product data: Often, the DataLayer lacks detailed information about products, such as category, brand, price, or SKU. Without this data, it is difficult to accurately monitor which products generate the most interest and have the potential for sale.
2. Incorrect or missing transaction information: Many modules do not include all key transaction-related parameters, such as order value, discounts, shipping costs, or order ID. As a result, reports in analytics tools are incomplete.
3. Lack of monitoring of the purchase process stages: The DataLayer should be designed to track each stage of the purchase process – from viewing products, adding to the cart, to completing the order. Missing this information makes it impossible to accurately analyze the "purchase funnel," which is key to optimizing conversions.

The role of custom DataLayer implementation

To fully leverage the capabilities of Google Tag Manager, a custom DataLayer implementation is required. This means that for each event (e.g., adding a product to the cart, completing a transaction), the appropriate data needs to be defined and passed to GTM.

For example, for an online store, you can define the DataLayer for different actions, such as:

window.dataLayer.push({
  'event': 'addToCart',
  'ecommerce': {
    'currencyCode': 'PLN',
    'add': {
      'products': [{
        'name': 'Laptop XYZ',
        'id': '12345',
        'price': '2999.00',
        'brand': 'Marka ABC',
        'category': 'Laptopy',
        'quantity': 1
      }]
    }
  }
});

This structure allows GTM to precisely collect and process data, which in turn enables the optimization of advertising campaigns, creation of remarketing, or conversion tracking with product- and transaction-level accuracy.

Summary

Implementing Google Tag Manager is more than just installing a module in the CMS. To fully utilize its capabilities, especially for advanced sites like online stores, proper DataLayer implementation is crucial. The modules available on the market often do not provide full integration, which is why a custom approach is necessary to monitor all key parameters and events on the website. Only then can the full potential of the analytics and marketing tools integrated with GTM be realized.

Implementing GTM with a correctly configured data layer allows for effective monitoring of user behavior, optimization of campaigns, and increased efficiency in marketing efforts.