Everything you want to know about Alexa.com
What is Traffic Rank?
The traffic rank is based on three months of aggregated historical traffic data from millions of Alexa Toolbar users and is a combined measure of page views and users (reach).
As a first step, Alexa computes the reach and number of page views for all sites on the Web on a daily basis.
The main Alexa traffic rank is based on the geometric mean of these two quantities averaged over time (so that the rank of a site reflects both the number of users who visit that site as well as the number of pages on the site viewed by those users).
The three-month change is determined by comparing the site’s current rank with its rank from three months ago.
For example, on July 1, the three-month change would show the difference between the rank based on traffic during the first quarter of the year and the rank based on traffic during the second quarter.
What are sites and Web hosts?
Traffic is computed for sites, which are typically defined at the domain level.
For example, the Web hosts www.msn.com, carpoint.msn.com and slate.msn.com are all treated as part of the same site, because they all reside on the same domain, msn.com.
An exception is personal home pages, which are treated separately if they can be automatically identified as such from the URLs in question.
Also, sites which are found to be serving the “same” content are generally counted together as the same site.
What is Reach?
Reach measures the number of users. Reach is typically expressed as the percentage of all Internet users”+” who visit a given site.
So, for example, if a site like yahoo.com has a reach of 28%, this means that if you took random samples of one million Internet users, you would on average find that”+” 280,000 of them visit yahoo.com.
Alexa expresses reach as number”+” of users per million. Alexa’s one-week and three-month average”+” reach are measures of daily reach, averaged over the specified”+” time period.
The reach rank is a ranking of all sites based solely”+” on their reach.
The three-month changes are determined by comparing”+” a site’s current reach and reach rank with its values from three month ago.
What are Page Views?
Page views measure the number of”+” pages viewed by Alexa Toolbar users. Multiple page views of”+” the same page made by the same user on the same day are counted”+” only once.
The page views per user numbers are the average numbers”+” of unique pages viewed per user per day by the users visiting”+” the site. The page view rank is a ranking of all sites based solely on the total number of page views (not page views per user).
The three-month changes are determined by comparing a sites current”+” page view numbers with those from three month ago.
Page views per million indicates what fraction of all the page views by toolbar users go to a particular site.
For example, if yahoo.com has 70,000″+” page views per million, this means that 7% of all page views go to yahoo.com.
If you summed the fractional page views over all sites, you would get 100% (this is not true of reach, since each user can of course visit more than one site.