If a site has Certified Metrics instead of estimated, that means its owner has installed code allowing us to directly measure their traffic.
These metrics have a greater level of accuracy, no matter what the ranking.
Estimates are more reliable the closer a site is to being ranked #1.
Global traffic ranks of 100,000 are subject to large fluctuations and should be considered rough estimates.
For these sites, we show estimated metrics based on traffic patterns across the web as a whole.
We identify these patterns by looking at the activity of millions of web users throughout the world, and using data normalization to correct for any biases.
The more traffic a site gets, the more data we have to calculate estimated metrics.
You should not have too much external links on your website.
Other wise this will affects your website negatively.