Search Ranking Studies: Trends and Important Factors

August 18, 2015

Moz-Future-Trends-Search-Ranking-Factors-Importance-Aug2015Annual search engine ranking studies have been recently released by both Moz and Searchmetrics [download page], relying on slightly different methods to arrive at their conclusions about what’s important and what’s not. According to the reports, the impact of relevant content continues to grow, while the number of links to a given page remains influential though potentially decreasing in value.

This article highlights some of the takeaways from the studies. Both are packed with data and insights and worth a look in their own right (follow the links above to access the results).

Moz Study

The annual study from Moz rests on a correlation study of 17,600 keyword search results from Google (in the US), as well as a survey of 150 search experts on the most important and trending factors.

The survey results show that in experts’ eyes, the most influential ranking factors (on a 10-point scale, where 10 is most influential) are:

  • Domain-level, link authority features (8.22);
  • Page-level link metrics (8.19); and
  • Page-level keyword and content-based metrics (7.87).

By comparison, search experts aren’t as convinced about the influence of domain-level keyword usage (5.88) and page-level social metrics (3.98), among others.

Experts also ranked individual factors within those broader ones, with the following emerging among the most influential:

  • Keyword present in the title element (8.34);
  • Uniqueness of the content on the page (7.85); and
  • Raw quantity of links from high-authority sites (7.78).

In other words, content quality and links continue to be important factors of search rankings, though as the Searchmetrics study argues (see below), the importance of links is declining.

How did those various factors hold up in the correlation analysis? A word about Moz’s analysis before continuing. The study looks at Spearman’s correlation with higher rankings, meaning that a higher number indicates that websites/pages with the given feature tended to rank higher on average than those without. The requisite disclaimer is of course that correlation does not equal causation!

Moving right along, here are some of the takeaways:

  • Correlations between on-page keyword use and rankings are low, and Moz suggests that “matching user intent is of utmost importance”;
  • Using HTTPS only has a very low (at 0.04, basically negligible) positive correlation;
  • Some page-level link-based features, such as page authority (0.37) and number of unique IPs linking to the URL (0.31), show some of the strongest positive correlations of all factors identified;
  • Link metrics about a domain hosting a page have somewhat strong correlation to rankings, but not as strong as page-level link metrics;
  • Use of anchor text is prominent in high-ranking results, led by the number of external root domains linking to the page with partial anchor text; and
  • Social and brand features including Facebook total count and shares on Google+ (both at 0.27) show some positive correlation with rankings, and Moz notes that “although there is strong reason to believe Google doesn’t use social share counts directly in its algorithm, there are many secondary SEO benefits to be gained through successful social sharing.”

Before moving on to the Searchmetrics study, the Moz survey also contained an interesting section on how some factors might change in impact on Google’s ranking algorithm over the next year.

The factors that search experts were most likely to see as increasing in impact are:

  • Mobile friendliness (88% believing this will increase);
  • Analysis of a site/page’s perceived value (81%);
  • Quantity/quality of instant answers provided in SERPs (79%);
  • Usage data such as CTR and dwell time (67%); and
  • Readability / usability design (67%).

By contrast, the effectiveness of paid links and the influence of anchor text are predicted to decline by a plurality of survey respondents.

Searchmetrics Study

Unlike the Moz study and previous editions of its own study, the Searchmetrics report goes beyond just correlations and also weighs the overall importance of individual factors based on a blend of big data analysis and an evaluation of how likely it is each factor can positively influence rankings. More about this decision here.

The importance of the various factors are thus assigned a score from -1 (negative impact) to 2 (very positive impact). Below, some of the highlights from the findings.

  • User signals appear to be one of the the most important factors, in fact assigned a score of 2+ in the study. Searchmetrics deemed it unnecessary to repeat its analysis of user signals this year, pointing instead to the data from last year’s analysis, but notes that signals such as the click-through rate, time on site and bounce rate are highly important as they allow for “an accurate insight as to whether the user was happy with the result.”
  • Another user experience factor, responsive design, has only has a very slight positive correlation but is assigned a high positive impact (a score of 2) in the overarching analysis. Clearly, mobile-friendliness is a factor that is expected to grow in importance, an uncontroversial position given “Mobilegeddon”.
  • Several content factors are assigned a very positive impact, including relevant terms, proof terms, and word count. (Interestingly, while having high correlations, social signals such as Facebook total and Google+ shares are assigned an importance rating of 0, meaning that they have no impact in Searchmetrics’ estimation.) Keywords – whether in the description or the body – are falling in influence, leading the analysts to note that “related terms, high semantic density and relevance of the text are much more important than keywords.”
  • Technical factors are an important, if not the most important, prerequisite for good rankings with good content, per the analysts, who note that this is unlikely to change. The most important technical factors, according to Searchmetrics, are site speed and domain SEO visibility. Among the takeaways? While HTTPS is becoming more relevant and perhaps even a Google ranking signal, it’s not a necessity for all sites. Also, “domains with a high SEO visibility also obtain higher rankings with their URLs.”
  • Finally, among backlink-related factors, referring domains is considered a more important factor than number of backlinks, although the latter has a more positive correlation with higher rankings. The analysts note that while the value of backlink quantity is still high, it is expected to decrease in the future.

There is much much more to these studies than can possibly be covered in a single article, so head on over to the reports for more.

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