Rankings, Smankings? (Part One)
Alexa admits to problems:
The traffic data are based on the set of toolbars that use Alexa data, which may not be a representative sample of the global Internet population. Known biases include (but are likely not limited to) the following:(And one should note that just a few years ago, on the matter of software adoption, they said this: "The rate of adoption of Alexa software in different parts of the world may vary widely due to advertising locality, language, and other geographic and cultural factors. For example, Korean sites are prominent among our top-ranked sites, but it is unknown to what extent this reflects high rates of general Internet usage in Korea.")
* Our users are disproportionately likely to visit sites that are featured on alexa.com such as amazon.com and archive.org, and traffic to these sites may be overcounted.
* The extent to which our sample may overcount or undercount users of the various browsers is unknown. Alexa's sample includes users of Internet Explorer, Firefox and Mozilla browsers. The AOL/Netscape and Opera browser is not supported, which means that sites operated by these companies may be undercounted.
* The extent to which our sample may overcount or undercount users of various operating systems is unknown. Alexa sample includes toolbars built for Windows, Macintosh and Linux.
* The rate of adoption of Alexa software in different parts of the world may vary widely due to advertising locality, language, and other geographic and cultural factors. For example, to some extent the prominence of Chinese sites among our top-ranked sites reflects known high rates of general Internet usage in China, but there may also be a disproportionate number of Chinese Alexa users.
* In some cases traffic data may also be adversely affected by our "site" definitions. With tens of millions of hosts on the Internet, our automated procedures for determining which hosts are serving the "same" content may be incorrect and/or out-of-date. Similarly, the determinations of domains and home pages may not always be accurate. When these determinations change (as they do periodically), there may be sudden artificial changes in the Alexa traffic rankings for some sites as a consequence.
* The Alexa Toolbar turns itself off on secure pages (https:). Sites with secure page views will be under-represented in the Alexa traffic data.
In addition to the biases above, the Alexa user base is only a sample of the Internet population, and sites with relatively low traffic will not be accurately ranked by Alexa due to the statistical limitations of the sample. Alexa's data come from a large sample of several million Alexa Toolbar users; however, this is not large enough to accurately determine the rankings of sites with fewer than roughly 1,000 total monthly visitors. Generally, Traffic Rankings of 100,000+ should be regarded as not reliable because the amount of data we receive is not statistically significant. Conversely, the more traffic a site receives (the closer it gets to the number 1 position), the more reliable its Traffic Ranking becomes.
I've got a friend who has had access to Nielsen//NetRatings from time to time, and she swears that once you get into the top 100,000 sites the numbers/rankings are virtually the same. She, and others, call the Top 100,000 The Big Boys.
But what does it all mean? How big is Big?
Alexa's blog explains:
Let's break it down by Alexa's Rankings, starting with the Top 500. Out of a total of 18 million sites to choose from, the Top 500 represent less than .003% of sites. But, as you would expect, these sites get a disproportionate amount of traffic. In fact they get 45% of all traffic. No, that's not a misprint. The odds that any Web surfer in the world is on a Top 500 site at any give time is about 50/50.These are the sites that Alexa swears it is accurate on.
Moving down the rankings, if you take Alexa's Top 100,000 sites you'll find that almost 3 out every 4 clicks are spoken for. In other words, almost 75% of all the traffic on the web goes to the sites in the Top 100K list, leaving the remaining 18 million or so sites to fight over the scraps.
Like the distribution of wealth on the planet, the distribution of traffic on the Web is extremely lopsided. The Top 500 are champagne and caviar. Sites 501 - 100,000 are meat and potatoes. The rest are hungry.
But is that true?
Alexa, like most things SEO, can be manipulated. I remember back when Backwash.com was pushing for increasing the ranking at Alexa, we were all encouraged to download the toolbar to record our visits to Backwash. Our ranking increased, and miraculously, while the site is at any given moment broken or not even live (likely accounting for the huge decrease in traffic), the site still has a nice Alexa ranking. Why? Well, here I'm going to refer you to Wow My Alexa Ranking is Great! Should I Trust It?.
One thing often overlooked in the Alexa accuracy problem is the bias that's built into their toolbar. Francesco Mapelli says it clearly:
Alexa's stats are based on the data collected by the users that installed the Alexa Toolbar. Fine. But who's intrested in downloading the alexa toolbar? What does the alexa toolbar offers?It's webmasters jockeying and researching using the Alexa toolbar; not average surfers.
* a search field (present in IE and Firefox, and with real search engines)
* popup blocking (present in IE and Firefox)
* traffic report
* site owner info
* related sites ( competitors? )
as you can see, the main features here are useful for webmasters, bloggers, site owners, SEOers etc.
This is not stuff for the average surfer!
As if this all weren't bad enough, check out We Bought An Alexa Ranking.
Any webmaster who checks their stats (and I don't mean you have to be religious about it like The Whore is) can quickly see if Alexa is at all accurate for their site. In my case, my sites must not swing Asian enough for it's really inaccurate.
So what can you use? Well, I'll get to that soon. I've got to study the info a bit more first.
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