# Audience measurement, tracking and product feeds

> Installing measurement that tells the truth, making it consent-compliant, and feeding marketplaces reliable product data — on PrestaShop, WooCommerce and Shopify.

- Source canonique : [https://allaux.fr/en/services/tracking](https://allaux.fr/en/services/tracking)
- Langue : EN
- Dernière mise à jour : 2026-09-30

## Wrong measurement costs more than no measurement

Most shops I take over do have a tag installed. The problem is almost never missing measurement: it is that the numbers it produces correspond to nothing. A purchase event fired twice because the tag sits both in the theme and in a module. Revenue that includes VAT on one side and not the other. Conversions attributed to “direct” because the payment domain is not excluded from referrals.

Setting an advertising budget on those numbers means flying blind while believing you can see. That is why I always start by checking what actually comes through, before adding anything.

## How I work on a tracking setup

1. **Observe what is really sent** — Google Tag Manager preview mode, the browser network tab, the actual dataLayer contents. Not the declared configuration: what the browser sends.
2. **Compare against the source of truth** — The shop’s own order count, same period, same time zone. The gap is never zero; it must be explainable.
3. **Fix the cause, not the symptom** — Remove the duplicate tag rather than filtering duplicates out of reports. A filter hides the problem and is lost at the first theme change.
4. **Write down what is in place** — Which tag, where, fired by what. Without that, the next person adds a second tag and the cycle starts again.

## Consent: two separate obligations that get conflated

On one side there is the legal obligation, in France and across the European Union, to obtain consent before setting trackers that are not strictly necessary. On the other, a requirement specific to Google: since March 2024, advertisers serving the European Economic Area and the United Kingdom must pass consent mode signals for their campaigns to keep working normally.

These are two different things. Meeting the second does not mean meeting the first. In its standard configuration, Google Analytics 4 does not meet the audience-measurement exemption criteria published by the French data protection authority, so in principle it requires consent. The pages in this section separate what the law requires from what a vendor requires.

## Product feeds: outgoing data matters as much as incoming

A rejected Merchant Center feed is not a technical detail: it means ads that stop running. The rejection reasons repeat from one shop to the next — a product identifier that changes on every export, a feed price that does not match the price shown on the product page, availability frozen on “in stock”, a sale price declared without a valid promotion period.

The same principles apply to the Meta catalogue and the Pinterest feed, each with its own constraints. I cover feed generation from PrestaShop, WooCommerce and Shopify, and how to read error messages that, taken literally, rarely point at the real cause.

## ChatGPT Ads conversion tracking

- **ChatGPT Ads conversion tracking** — OpenAI pixel, Conversions API, oppref and consent: the same pixel-plus-server logic, applied to ChatGPT ads. ([/services/tracking/suivi-conversions-chatgpt-ads](/services/tracking/suivi-conversions-chatgpt-ads))
- **ChatGPT Ads module for PrestaShop** — Deduplicated OpenAI pixel and Conversions API, oppref kept until the order, consent respected: built and installed by me. ([/prestashop/module-chatgpt-ads](/prestashop/module-chatgpt-ads))
- **ChatGPT Ads extension for WooCommerce** — OpenAI pixel and Conversions API, compatible with HPOS, the block checkout and consent plugins: built and installed by me. ([/wordpress-woocommerce/extension-chatgpt-ads](/wordpress-woocommerce/extension-chatgpt-ads))

## What I do not do

> I do not run your advertising campaigns and I do not advise on bidding. I install and repair measurement: what fires, what is sent, what is received. Acquisition strategy is a different trade.

## FAQ

### My Analytics shows fewer orders than my shop. Is that normal?

A gap always exists: ad blockers, refused consent, visitors who close the page before the tag loads. A gap in the tens of percent is structural, not a bug. What should worry you is a gap that changes abruptly, or orders counted twice.

### Should I use Google Tag Manager or install the tag directly?

If you have a single tag and no intention of adding more, direct installation is simpler and faster. As soon as several tools are involved, or someone other than the developer needs to make changes, a tag manager saves reopening the theme every time.

### Is my theme’s tracking module enough?

Often yes for page views, rarely for purchase events. It is also the leading cause of double counting: the module places its tag, then someone adds a second one without knowing the first exists.

### Do you work on a site already in production?

Yes, that is the usual case. Tags can be changed without downtime. When a theme change is needed, I prepare and test it before putting it live.