Mar 232018

The next SEO experiment I’d like to discuss results for is the MDN “Competitive Content Analysis” experiment. In this experiment, performed through December into early January, involved selecting two of the top search terms that resulted in MDN being included in search results—one of them where MDN is highly-placed but not at #1, and one where MDN is listed far down in the search results despite having good content available.

The result is a comparison of the quality of our content and our SEO against other sites that document these technology areas. With that information in hand, we can look at the competition’s content and make decisions as to what changes to make to MDN to help bring us up in the search rankings.

The two keywords we selected:

  • “tr”: For this term, we were the #2 result on Google, behind w3schools.
  • html colors”: For this keyword, we were in 27th place. That’s terrible!

These are terms we should be highly placed for. We have a number of pages that should serve as good destinations for these keywords. The job of this experiment: to try to make that be the case.

The content updates

For each of the two keywords, the goal of the experiment was to improve our page rank for the keywords in question; at least one MDN page should be near or at the top of the results list. This means that for each keyword, we need to choose a preferred “optimum” destination as well as any other pages that might make sense for that keyword (especially if it’s combined with other keywords).

To accomplish that involves updating the content of each of those pages to make sure they’re as good as possible, but also to improve the content of pages that link to the pages that should show up on search results. The goal is to improve the relevant pages’ visibility to search as well as their content quality, in order to improve page position in the search results.

Things to look for

So, for each page that should be linked to the target pages, as well as the target pages themselves, these things need to be evaluated and improved as needed:

  • Add appropriate links back and forth between each page and the target pages.
  • Is the content clear and thorough?
  • Make sure there’s interactive content, such as new interactive examples.
  • Ensure the page’s layout and content hierarchy is up-to-date with our current content structure guidelines.
  • Examine web analytics data to determine what improvements the data suggest should be done beyond these items.

Pages reviewed and/or updated for “tr”

The primary page, obviously, is this one in the HTML element reference:

These pages are closely related and were also reviewed and in most cases updated (sometimes extensively) as part of the experiment:

A secondary group of pages which I felt to be a lower priority to change but still wound up reviewing and in many cases updating:

Pages reviewed and/or updated for “html colors”

This one is interesting in that “html colors” doesn’t directly correlate to a specific page as easily. However, we selected the following pages to update and test:

The problem with this keyword, “html colors”, is that generally what people really want is CSS colors, so you have to try to encourage Google to route people to stuff in the CSS documentation instead of elsewhere. This involves ensuring that you refer to HTML specifically in each page in appropriate ways.

I’ve opted in general to consider the CSS <color> value page to be the destination for this, for reference purposes, with the article “Applying color” being a new one I created to use as a landing page for all things color related to route people to useful guide pages.

The results

As was the case with previous experiments, we only allowed about 60 days for the Google to pick up and fully internalize the changes as well as for user reactions to affect the outcome, despite the fact that 90 days is usually the minimum time you run these tests for, with six months being preferred. However, we have had to compress our schedule for the experiments. We will, as before, continue to watch the results over time.

Results for the “tr” keyword

The pages updated to improve their placement when the “tr” keyword is used in Google search, as well as the amount of change over time seen for each, is shown in the table below. These were the pages which were updated and which appeared in search results analysis for the selected period of time.

Change (%)



Clicks Position CTR
HTML/Element/tr -43.22% 124.57% 2.58% 285.71%
HTML/Element/table 26.68% 27.02% -2.90% 0.00%
HTML/Element/template 27.02% 9.21% -15.45% -14.05%
API/HTMLTableRowElement/insertCell -2.78% -23.91% -2.16% -21.77%
HTML/Element/thead 38.82% 19.70% 0.00% -13.67%
HTML/Element/tbody 42.72% 100.52% 14.19% 40.68%
HTML/Element/tfoot 8.90% 11.29% 2.64% 2.18%
HTML/Element/th -50.32% 3.43% 0.39% 106.25%
HTML/Element/td 20.05% 40.27% -8.04% 17.01%

The data is interesting. Impression counts are generally up, as are clicks and search engine results page (SERP) position. Interestingly, the main <tr> page, the primary page for this keyword, has lost impressions yet gained clicks, with the CTR skyrocketing by a sizeable 285%. This means that people are seeing better search results when searching just for “tr”, and getting right to that page more often than before we began.

Results for the “html colors” keyword

The table below shows the pages updated for the “html colors” keyword and the amount of change seen in the Google activity for each page.

Page Change Impressions (%) Change Clicks (%) Change Position (Absolute) Change Position (%) Change CTR (%) +28.61% +19.88% -0.99 -4.54% -6.78% -43.88% -38.17% -2.71 -21.20% +10.17% +51.59% +33.33% +3.28 +48.62% -12.04% +34.87% +29.55% -1.35 -11.34% -3.94% +9.03% +19.26% -0.17 -2.46% +9.38% +36.02% +36.98% -0.09 -1.38% +0.71% +23.04% +23.42% +0.03 +0.34% +0.31% +14.95% +34.09% -1.21 -10.26% +16.65% -10.78% +6.68% +1.76 +24.78% +19.56% +830.70% +773.91% -0.97 -12.42% -6.10% +3254.57% +3429.41% -1.45 -21.98% +5.21% +50.32% +45.21% -0.56 -4.83% -3.40% +31.15% +25.57% -0.44 -4.44% -4.25%

These results are also quite promising, especially since time did not permit me to make as many changes to this content as I’d have liked. The changes for the color value type page are good; nearly 15% increase in impressions and a very good 34% rise in clicks means a health boost to CTR. Ironically, though, our position in search results dropped by nearly 1.25 points., or 10%.

The approximate 23% increase in both impressions and clicks on the CSS color attribute is quite good, and I’m pleased by the 10% gain in CTR for the learning area article on styling box backgrounds.

Almost every page sees significant gains in both impressions and clicks (take a look at text-decoration-color, in particular, with over 3000% growth!).

The sea of red is worrisome at first glance, but I think what’s happening here is that because of the improvements in impression counts (that is, how often users see these pages on Google), they are prone to reaching the page they really want more quickly. Note which pages are the ones with the positive click-through rate (CTR), which is the ratio of clicks divided by impressions. This is in order of highest change in CTR to lowest:


What I believe we’re seeing is this: due to the improvements to SEO (and potentially other factors), all of the color-related pages are getting more traffic. However, the ones in the list above are the ones seeing the most benefit; they’re less prone to showing up at inappropriate times and more likely to be clicked when they are presented to the user. This is a good sign.

Over time, I would hope to improve the SEO further to help bring the search results positions up for these pages, but that takes a lot more time than we’ve given these pages so far.


For this experiment, the known uncertainties (an oxymoron, but we’ll go with that term anyway) include:

  • As before, the elapsed time was far too share to get viable data for this experiment. We will examine the data again in a few months to see how things are progressing.
  • This project had additional time constraints that led me not to make as many changes as I might have preferred, especially for the “html colors” keyword. The results may have been significantly different had more time been available, but that’s going to be common in real-world work anyway.
  • Overall site growth during the time we ran this experiment also likely inflated the results somewhat.


After sharing these results with Kadir and Chris, we came to the following initial conclusions:

  • This is promising, and should be pursued for pages which already have low-to-moderate traffic.
  • Regardless of when we begin general work to perform and make changes as a result of competitive content analysis, we should immediately update MDN’s contributor guides to incorporate recommended changes.
  • The results suggest that content analysis should be a high-priority part of our SEO toolbox. Increasing our internal link coverage and making documents relate to each other creates a better environment for search engine crawlers to accumulate good data.
  • We’ll re-evaluate the results in a few months after more data has accumulated.

If you have questions or comments about this experiment or its results, please feel free to post to this topic on Mozilla’s Discourse forum.

 Posted by at 4:46 PM