Google had maintained a complete secrecy about the algorithm it uses to generate site links. Google includes pages in the sitelinks that don't appear to be the healthiest pages in traffic acquisition, engagement, or any other supporting data point. Why is Google selecting these pages? Below are three possible explanations:

• Something for Everyone.
• Search Trends.
• Testing.

Examining web analytics data on site content and to try and "save users’ time" are something organizations do on a daily basis. There is a common assumption that Google has a clever way of determining the popularity of site pages without knowing the website analytics.The method that Google utilizes to determine sitelinks is still somewhat of a mystery. But data shows that Google is anticipating the popularity and health of pages within a site and in many cases including one sitelink that is not typically very popular on the site.

Mark Ryan, Lead Analyst, Extractable writes on this aspect in detail. To read, visit the following link:

http://www.clickz.com/clickz/column/2342233/comparing-google-sitelinks-with-google-analytics-data