New study: which web page elements lead to high Google rankings?

The German company Sistrix analyzed the web page elements of top ranked pages in Google to find out which elements lead to high Google rankings. They analyzed 10,000 random keywords, and for every keyword, they analyzed the top 100 Google search results.

Which web page elements lead to high Google rankings?

Sistrix analyzed the influence of the following web page elements: web page title, web page body, headline tags, bold and strong tags, image file names, images alt text, domain name, path, parameters, file size, inbound links and PageRank.

• Keywords in the title tag seem to be important for high rankings on Google. It is also important that the targeted keywords are mentioned in the body tag, although the title tag seems to be more important.
• Keywords in H2-H6 headline tags seem to have an influence on the rankings while keywords in H1 headline tags don't seem to have an effect.
• Using keywords in bold or strong tags seems to have a slight effect on the top rankings. Web pages that used the keywords in image file names often had higher rankings. The same seems to be true for keywords in image alt attributes.
• Websites that use the targeted keyword in the domain name often had high rankings. It might be that these sites get many inbound links with the domain name as the link text.
• Keywords in the file path don't seem to have a positive effect on the Google rankings of the analyzed web sites. Web pages that use very few parameters in the URL (?id=123, etc.) or no parameters at all tend to get higher rankings than URLs that contain many parameters.
• The file size doesn't seem to influence the ranking of a web page on Google although smaller sites tend to have slightly higher rankings.
  It's no surprise that the number of inbound links and the PageRank had a large influence on the page rankings on Google. The top result on Google has usually about four times as many links as result number 11.