The Visconti-Sforza Deck of 1428 is an example of the absence of these signs.
In 1470 there is already an image of classical gods and astrological symbols in a deck of cards Montegna …
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.
Estimates are more reliable the closer a site is to being ranked #1.