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How to measure eCommerce improvements for users

Author: Alan Kent

An image of author Alan Kent with various search-related iconography, including a bar chart, a pie chart, and faux clicks and impressions metrics

You make a change on your eCommerce site. It’s just a little change—the color of a button, to make it consistent with your site’s corporate colors. Job done and off you go with the rest of your day.

A week later, you wonder why your sales feel a bit lower. Oh well, there is always next week. The panic does not set in until the end of the month. What happened? Why has your online business lost its mojo? Where have all the sales gone? How do you track down the problem and fix it?

The tale above is based on a true story told to me by a real merchant. Someone changed the color of a key call-to-action button and they saw a 30% drop in click-through rate to their best-selling product. However, the real story deviated in one key point—the merchant had analytics in place so they quickly spotted the impact of the change and reverted it.

Why did a seemingly minor site change have such a big impact? The new button color no longer stood out from the rest of the page, so shoppers did not notice it and moved on.

The moral of this story? It’s the well known adage “you can’t improve what you don’t measure” (often attributed to Peter Drucker).

But how do you put this adage into practice on your own website?

Table of contents:

The importance of measuring your eCommerce website performance

The first step to protect you from becoming a cautionary tale like the one above is to measure important shopper actions on your site. Do you know how many people visit different pages on your site? If the traffic changed, would you be aware?

For eCommerce websites, there are common page flows that shoppers follow, such as:

Homepage > category page > product listing page > conversion (checkout)

Do you know how many users (as an absolute number or a percentage) go from your homepage to a category page? Or from a category page to a product page? If you made a change, would you know if that change helped or hindered shoppers?

You will lose a percentage of traffic at each transition, but if you can identify a particular step in your customer journey where you are losing an unexpected number of users, then you have a chance of fixing the problem. Otherwise, resolving the issue may feel like a wild goose chase, with you investigating numerous potential causes, such as:

  • Maybe one of your pages is confusing shoppers as to how to proceed

  • Technical problems, like broken links or faulty JavaScript

  • Cross-browser compatibility of new JavaScript you added to your site

Many sites and SEO experts focus on driving traffic from search engines to their pages, and there are many great tools to help analyze such traffic (like Google Search Console). Search engine traffic matters, but on eCommerce sites, what shoppers experience after they arrive matters, too. So, other tools (in addition to some standard SEO tools) may be needed to help you effectively diagnose problems.

How do you pick what eCommerce metrics to measure and track? While you could try to track everything, that’s probably not the best method as collecting too many metrics via third-party scripts can negatively impact the speed of your site (more on this later), and slower sites generally don’t convert as well. So think about the right metrics to collect so that you can keep bringing in traffic and converting it without sacrificing user experience.

Selecting the right eCommerce metrics to track

Like most things in life, deciding what to monitor is about compromise. Collecting metrics can negatively impact the performance of your site. And, this data is only worth the compromise in user experience if you actually put it to use to further your business goals.

The user experience impact of collecting analytics can be hard to predict as it is influenced by multiple factors, including:

  • Mobile devices generally have lower performance and network bandwidth capacity than laptops or desktops. You should design for lower-end mobile devices, not the latest high-end device.

  • First-time shoppers on your site may have more JavaScript to download. This JavaScript has to be downloaded (competing with other network requests) and parsed by the web browser (consuming CPU and memory).

  • There is more code monitoring for operations shoppers perform on your site, which can slow down how responsive those operations are.

  • Collected metrics data have to be sent to your analytics collection site.

User interactions on a web page need to complete in a tenth of a second to feel instantaneous. At one second, interaction delays start to interrupt a shopper’s thought process. The more metrics that are collected, the more JavaScript code needs to execute, which can negatively impact the responsiveness of the website. (Good implementations try to mitigate the impact of metrics collection by backgrounding as much work as possible, but collecting more metrics will always add more overhead.)

But the impact of not collecting data can be worse. If your only insight into site issues is a drop in your sales revenue, that may be too late. If you have made multiple changes, how do you decide which ones to roll back? And how are you even sure that it was something on your site that triggered the revenue drop?

To that end, here are some common eCommerce site metrics that, when monitored regularly, can help you troubleshoot conversion issues and improve performance:

  • Bounce rate — Are users leaving your web pages as soon as they arrive from a search engine? That may indicate your page needs to be improved, or it is matching the wrong searches.

  • Impressions — What pages on your site are shoppers visiting the most? Do you know which products are gaining interest over time? Which are losing popularity? What about the overall trends of users going from category pages to product pages? Did a site-wide template change impact site traffic?

  • Click-through rate — Are users clicking on the links you want them to, including for special offers and email signups? Are they moving through your site towards checkout, and if not, where do they stop?

  • Order value — Is the average order value of shoppers going up or down? Do some special offers increase the order size more than others?

  • Abandonment rate — How many users get to checkout but do not proceed? Is there a problem without your payment processor causing friction, or were there unexpected charges that shoppers did not realize earlier?

There are many more metrics that may be important for you. Before you finalize your list of metrics, review your business objectives. Do you want to increase your number of sales or the average order value? Do you value new or returning customers more? Do you want to know how effective your marketing campaigns are? Once you know your business goals, make sure you are collecting the right metrics to measure your progress.

Popular tools for eCommerce measurement

There are multiple free and paid tools available to help you collect and visualize metrics. The tools you should consider will depend on what you need to measure.

Changes in web traffic can be measured with multiple tools:

  • Built-in analytics (for example, Wix Analytics) generally offer a quick and easy overview of your traffic from search engines.

  • Google Search Console (GSC) can help you troubleshoot a multitude of potential issues related to getting traffic from Google. Note: Wix users have access to GSC data within Wix Analytics.

  • Third-party SEO tools like Semrush, which can help you select the best keywords to increase traffic from search engines

  • Your platform’s app marketplace may also have some useful enhanced analytic tools (for example, Visitor Analytics and other similar apps are available in the Wix App Market).

Changes in shopper behavior are commonly measured using Google Analytics, but there are many alternatives available with different strengths and price tags. Examples include:

  • Adobe Analytics — Another platform popular with larger customers

  • Amplitude — An analytics platform with built in support for A/B testing

  • Matomo — A popular set of open-source tools (with commercial offerings), with options for you to keep collected metrics local to your site

  • Hotjar — Another platform with tools such as visualization showing which parts of a page visitors view

Changes in web performance, like page speed, can be measured with tools such as Google’s PageSpeed Insights, which leverages real-world data from Chrome browsers and analyzes site pages (without making changes to your site).

Using website data to see the impact of site changes

So you are collecting metrics for your site. Congratulations! The next step is to start running experiments based on the collected metrics.

Longitudinal testing

Longitudinal testing is a simple approach for testing site changes that involves looking at your metrics before and after making SEO updates or other site changes. To use this approach, you need to keep track of what site changes you made and when. Make sure you collect enough data over a long enough period of time to be confident in the results, and remember that staying organized is crucial to ensure the integrity of your test (the ability to view your site history, either as a built-in CMS feature or plugin, can be very useful).

A general knowledge of statistics is useful to understand how much data you need to be confident in the impact of a change. If your site does not have much traffic, you will need to collect traffic for a longer period of time to have confidence in the results. If you have access to an analytics tool, see if it includes confidence scores for reported data so you know how long you should run the test in order to trust the results.

For all its strengths, longitudinal testing also presents challenges: How can you determine which (of multiple) changes impacted your metrics? Could seasonality impact the test results? The popularity of ski gear fluctuates with the weather, so comparing two weeks of data before and after a site change may be misleading if the weather changed during that time. How can you make sure the metrics you collect capture the impact of your site change and not other influences? This is where A/B testing can be helpful.

A/B testing

A more advanced testing approach is A/B testing. With A/B testing, you show some of your site visitors a new experience and some the old experience. Because you are measuring both experiences at the same time, you don’t encounter many of the problems of longitudinal testing.

So, why doesn’t everyone use A/B testing? One reason is that A/B testing is generally harder to implement (Note: Wix site owners can conduct A/B tests by creating a test site). And as mentioned earlier, another practical problem is it can slow down your site and slower site speed can negatively impact your conversion metrics. So, you need to be careful that running an A/B test is not hurting your site/business/customers during the test.

Getting started with eCommerce metrics collection

Are you finding it hard to get started on your data insights journey? Consider starting small and expanding over time. Collect some basic site metrics and try to use the metrics to measure the impact of a site change. Even if you fail, you will start to learn what metrics are useful.

Next, make it a habit. Add a regular interval on your calendar (such as monthly) to review your metrics. Or when you make a site change, add a calendar reminder for a few weeks later to check your site metrics.

If you want to consistently increase revenue from your eCommerce site over time, you will want to put tools in place to measure the impact of site changes. The impact of seemingly minor changes can be significant. Without collected metrics, rolling out site changes is like playing a game of chance, but one where you don’t know if you won or lost until later. So if you are not collecting metrics, make that first step. Your platform probably has some metrics built in. Why not start now?


Alan Kent

Alan has been involved in search for over 30 years, and eCommerce for over 10 at eBay and Magento. As part of the Google Search Relations team, Alan focused on educating merchants to get the most out of Google Search with documentation and videos. Twitter | Linkedin


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