The biggest unknown in SEO is always the algorithm. Many myths and rumors surround the what and how of Google results and their sorting and how you can best influence them.
At Searchmetrics we continually aggregate billions of data points a month and naturally look for the answer to the question: “Which factors are relevant for a good ranking in Google search results?” With this study we will get closer to the answer on the basis of 10,000 selected top-keywords, 300,000 websites and millions of links, shares and tweets. We will compare potential ranking factors and thus website characteristics with their corresponding Google rankings by assessing their statistical correlation. For example, if there are many pages in the top positions of analyzed SERPs with keyword title tags, then we have identified a high correlation.
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A few highlights from our inquiry
- Social media signals show extremely high correlation: social signals from Facebook, Twitter and Google+ are frequently associated with good rankings in Google’s index. Too much advertising is detrimental: for the first time we are seeing sites with too many advertisements struggling to rank well. However, the problem apparently relates only to AdSense adblocks…
- Backlinks are still important but quantity is not the only important thing: even though the number of backlinks is still the most powerful factor, links with stop words and ‘nofollow’ should also be included in the link-mix.
- Brands leverage classic SEO signals: apparently pages with strong brands do not need to be as concerned with the areas of title tags, headings etc. According to our figures, this group operates under different rules.
- Keyword domains still frequently attract top results: despite all the rumors to the contrary, keyword domains are still alive and well and are often in the top rankings.
The clearest way to present the correlations between different factors and Google search results is Spearman’s rank correlation coefficient.
The larger the bar, the greater the correlation. The correlation coefficient is displayed on the x-axis. Greater values along the x-axis (e.g. Facebook Shares) have a positive correlation (the more, the better) while lower values (Title Character Length) have a negative correlation. Therefore, we can say that the largest correlation occurs between Facebook Shares and the lowest between the Position of Title Keywords. With negative values, the correlation between title character length can be seen: the shorter the title is, the better the ranking – more about this later.
Data for this study was collected in February and March 2012. In the results, you can see the effects of the various Panda Updates that have greatly changed the look of results since the start of 2011.
The most important factors
These values are only really useful when they are organized thematically, examples given and the structures behind them ascertained. This is the goal of our study.
Social signals are as strong as ever
Facebook and Twitter signals correlate as follows with higher rankings:
The different Facebook metrics feature the highest values, of which ‘shares’ appear to have the strongest association, followed directly by the number of backlinks in the overall summary. Twitter is far behind these values but is still the 6th strongest metric in our analysis behind Facebook and the number of backlinks.
A note on Google+: analyzing Google +1s with a Spearman correlation, we found a significant result of 0.41. From this we can assume that the quantity of +1s has the strongest correlation of any of the metrics analyzed in the study.
However, we have not included this figure in the overview because we consider it to be too unreliable. This is because Google+ does not currently have enough users and the possibility of a +1 leading directly to changes in SERPs follows accordingly, since pages receive +1s in the order that they would already be placed without them. When Google+ has values that are stronger and more independent from SERPs, these values will also be included in the overview. That Google is trying to make Google+ an important player is indisputable and therefore SEOs should be sure to keep an eye on further developments.
(Clumsy) advertisements are an obstacle
Too many and/or excessively clumsy advertisements were presumed to be a factor in the Panda Update and its successors. The data in this study support this assumption as all our analyzed advertisement factors returned a negative correlation:
General AdLinks (common integrations e.g. Commission Junction, AdSense and others) are slightly less negative than the use of AdSense alone. However it is important to note that the correlation value above is for AdLinks for all integrations including AdSense. If we take the % trend for AdSense integration and all other analyzed competitor networks according to rankings, we arrive at a surprising conclusion:
We can clearly see that AdSense advertisements drop sharply among the top rankings. However, all other forms of advertisement that we analyzed have in fact remained consistent. The bottom line is, then, that only AdSense has a negative correlation.
Therefore, at the moment it seems that we are more likely to find sites with fewer traditional advertisement integrations in top rankings. Of course, this might also have something to do with brand sites – Sony, for instance, has no banner ads on their product pages.
Recently Google even confirmed directly that particularly prominent, distracting or above-the-fold ads could lead to ranking problems – and it is precisely this trend that we can see in our correlation data. However, we continue to provide additional information since these factors only appear to be relevant in the top 10 results and because AdSense seems to feature more often on poorly ranking sites than those with better rankings.
Backlinks are still SEO gold – but standards are rising
Regardless of the rising power of social media, backlinks are and will continue to be one of the most critical factors in achieving good rankings. The correlation data supports this – following Facebook metrics, the number of backlinks is the factor that most strongly correlates with good rankings…