Quality content creation is considered the most effective SEO tactic (and also the most difficult to execute) per recent Ascend2 research, and a new Google search rankings study from SearchMetrics [download page] gives further weight to the importance of quality, relevant content. Indeed, the study notes that “content is no longer an addition to, but is the main focus of, SEO.”
The analysis yields correlation (Spearman) figures for 51 rankings factors, with the requisite disclaimer: “a good search position cannot simply be achieved by ticking a few of these boxes. The search engine assessment of the relevance of pages is always multifaceted, and ranking positions are based on the interaction of many different factors. Correlations described here are not to be interpreted as causal relationships across-the-board.”
Following, some key results from the study, organized by areas.
The importance of keywords in the URL and domain name has disappeared over the past couple of years, to the extent that this “no longer exists as a ranking factor.” However, there are some onpage keyword factors that have a positive correlation with rankings; namely, keywords in description, the title and the H1 heading, with the latter two increasing in importance fro last year. The authors note that “the sooner the better” applies to keywords in titles.
Meanwhile, although there isn’t a strong correlation between load speeds and rankings, this owes in part to Wikipedia results flattening the curve, and the analysts note that “a quick page load time is one of the basic requirements for good rankings.”
Also of note: a solid technical site structure and performance is “one of the absolute SEO basics.”
The study notes that the best-ranking content tends to have higher word-counts, “semantically comprehensive wording,” and includes rich media.
HTML length, text character length and word count have increased in importance from last year – although the authors caution that it’s not simply a matter of more content, but rather more relevant content.
Meanwhile, the number of external links and the image count have decreased in influence, and advertising (including AdSense Blocks and AdSense) continues to be negatively correlated.
Relevant terms (“semantically removed relatives of the main keywords”) and proof terms are highly correlated on-page content features this year, not having been included in last year’s analysis. While term frequency and the frequency of other relevant and related terms remain important, the study authors note that overuse of keyword terms will be quickly recognized as spam. In other words, the main focus is on content quality rather than the number of links or keywords.
Finally, internal link structure is considered a “vital component” of performance, and the analysts note that “many companies and website operators make the mistake of focusing on external links rather than trying to optimize the user experience and internal link flow.”
These are considered “probably the most important SEO metric on the off page side,” with the number of backlinks being the most highly correlated ranking factor in this area. However, this has decreased in importance from last year. In its place, the SEO visibility of the back-linking URL has become more influential.
Other backlink factors that have a fairly strong correlation with rankings are the number of referring domains to the home page and the number of news-domain links, a reflection of the media coverage generated by larger brands.
Meanwhile, backlink quality is still very important, as evidenced by positive correlations for new backlinks and share of no-follow links.
Social signals, once the darling of SEO ranking factors, appear to have decreased in importance this year. While social signals such as Google +1s, Facebook shares and Facebook comments continue to have high correlations on average, this is an area in which marketers should be careful not to confuse correlation with causality, as pages in top-ranked positions tend to carry more social signals.
The study notes that brands are at the top of the rankings “even if there are certain factors they do not fulfill which lower-ranked sites do,” suggesting special treatment for them. What appears to work in brands’ favor is their excellent backlink profile and links to sources with high SEO visibility (see above).
Interestingly, the report also indicates that “Google seems to give great influence to another factor, niche Brands.” These smaller domains that are targeted to a specific area tend to rank well for niche terms and even for more generic, yet related, terms.
As anecdotally known, Wikipedia often ranks highly, typically in the second position for a variety of short and generic keywords.
The positive correlation for click-through rate, while expected, is the “highest correlation that has ever been calculated for a factor of ranking studies.” As with time on site, bounce rate also emerges as a signal of quality.
About the Data: A detailed description of the study’s methodology can be found by accessign the link above.