Why You Need to Know Your Pages’ Conversion Impact Score

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Why You Need to Know Your Pages’ Conversion Impact Score

Conversions are the lifeblood of your business. If you touch your company’s website in any way—be it design, marketing, or development—then your actions have an impact on conversions. You need to understand what that impact is.

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There’s a widely held belief that the only people who need to care about conversions are people in sales and business development. Wrong.

Conversions are the lifeblood of your business. If you touch your company’s website in any way—be it design, marketing, or development—then your actions have an impact on conversions. You need to understand what that impact is.

I’m going to explain how to determine which pages you should focus on optimizing in order to increase conversions and, ultimately, deliver the highest ROI.

What Is a Conversion?

A conversion is what happens when a person who’s browsing a site converts to being a user or buyer of the service or product that site offers. So if you’re a SaaS vendor, a conversion happens when a person signs up to use your service—or if you’re an e-commerce shop, when a person buys something. Conversions can also include actions like signing up for a newsletter or making a donation.

The conversion funnel is the start-to-finish path that a user takes when they convert from browsing to buying/ downloading/etc. A conversion funnel for an ecommerce site might look something like this (note that percentages are arbitrary and extremely optimistic):

Image title

Conversion rate is the percentage of total user sessions that result in a conversion. In the conversion funnel graphic above, the conversion rate is the number of people who completed a purchase: 10%. Conversion rates are typically in the 2-5% range. Anything higher than that is amazing.

For a site that does hundreds of thousands of dollars worth of transactions in a day, even tiny changes in conversion rate—such as increasing from 2.1% to 2.2%—can have a huge impact on revenue.

Performance Slowdowns Affect Conversions Differently on Different Pages

When pages get slower, conversion rates suffer. But some types of pages suffer more than others. For example, on retail sites, slow “browse” pages have

a greater negative impact on performance than slow “checkout” pages.

Here you can see that, for one ecommerce vendor, the conversion rate shrank by about 50% when the load time for “browse” pages increased from 1 to 6 seconds (right, top):

For the same retailer, the impact on conversion rate was much less when checkout pages degraded in speed (right, bottom):

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Looking at these two graphs side by side, you could be tempted to deduce that, because conversions were hurt more by slow “browse” pages than by slow “checkout” pages, the site owner should focus energy on optimizing the browse pages. This might be true—but it might not be true, too. This is where Conversion Impact Scoring comes in.

What Is the Conversion Impact Score?

The Conversion Impact Score is a relative score that ranks page groups by their propensity to negatively impact conversions due to high load times. For each page group, the Conversion Impact Score is calculated using the proportion of overall requests that are associated with that group, along with the correlation between its load times and number of conversions. The more negative the score, the more detrimental to conversions that high load times for that page group are, relative to the other page groups.

In other words, Conversion Impact Scoring answers this question: how much impact does the performance of this page have on conversions?

Case Study: How To Use Conversion Impact Scoring To Prioritize Performance Optimization

Now let’s walk through how to use Conversion Impact Scores to make decisions about optimizing your pages.

In the table below, you can see the Conversion Impact Scores and load times for a set of page groups on a retail site. The second column represents the Conversion Impact Score for each page group, and the third column represents the median page load time for each group. For a complete graph of these details, click here.

The groups are ranked from those with the highest Conversion Impact Scores (such as product and category pages; in other words, pages viewed in the “browse” phase of the conversion funnel) to pages with the lowest scores (such as checkout and sign-in pages).

Page Group

Relative Conversion Impact Score

Median Full Page Load Time (seconds)

Product Detail Page



Category Browse 1






Choose Your Country



Shopping Bag



Checkout – Send To






Checkout – Order Confirmation



Account – SignIn



Some quick observations:

  • Some of the fastest page groups—such as Shopping Bag and Wishlist—have relatively low Conversion Impact Scores. This means that page speed isn’t a significant factor in how well these pages convert.
  • The page groups with the highest Conversion Impact Scores— such as Product and Category pages—have acceptable load times in the 3-second range.
  • The slowest group is Checkout – SendTo, followed by Home, Account – SignIn and Checkout – Order Confirmation.

Without knowing the Conversion Impact Scores for these page groups, you might focus on optimizing pages according to how slow they load. Looking at load time, this is the order in which you’d prioritize fixing these groups:

  1. Checkout – SendTo
  2. Home
  3. Account – SignIn
  4. Checkout – OrderConfirmation
  5. Category Browse 1

Now here’s how some of these assumptions are incorrect:

Assumption #1: Prioritizing the Checkout – SendTo Page Group Because It’s The Slowest

If you looked only at page load times, you might believe that you need to prioritize the Checkout – SendTo group because its performance is dramatically poorer than the other groups. But if you knew its Conversion Impact Score, you’d realize that page speed doesn’t have much impact on conversion rate, so making this group faster wouldn’t be the best use of your limited optimization resources.

Assumption #2: Tackling The Account – SignIn Page Group Next

Also, if you were to look exclusively at load times, you might believe that when you’re done with optimizing the Checkout – SendTo group, you should focus next on addressing performance issues on the Account – SignIn group. While these pages have a high enough Conversion Impact Score that they merit addressing, they shouldn’t rank high up on your list.

Assumption #3: Not Worrying About the Category Browse 1 And Product Detail Page Groups Because They Seem Relatively Fast

Still looking solely at load times, you might also guess that, because these pages look fairly speedy, you don’t need to worry about them. This is where you’d make your biggest mistake. Because these groups have the highest Conversion Impact Scores, they have the potential to deliver the most benefit to you if you make them faster.


Knowing the Conversion Impact Scores for this set of page groups, this is the order in which you might actually want to prioritize their optimization to give you the best ROI:

  1. Home
  2. Category Browse 1
  3. Product Detail Page
  4. Choose Your Country
  5. Shopping Bag

For more insights on monitoring, application logs, and performance management, get your free copy of the new DZone Guide to Performance and Monitoring, Volume III!

conversion, conversion impact score, performance

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