Alexa computes traffic rankings by analyzing the Web usage of millions of Alexa Toolbar users and data obtained from other, diverse traffic data sources. The information is sorted, sifted, anonymized, counted, and computed, until, finally, we get the traffic rankings shown in the Alexa service. The process is relatively complex, but if you have a need to know, please read on.

The traffic rank is based on three months of aggregated historical traffic data from millions of Alexa Toolbar users and data obtained from other, diverse traffic data sources, 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.

So you see, Alexa analyze the web usage of millions of Alexa Toolbar users and that’s their main source for traffic analysis.

Why isn’t accurate?

I run a couple of websites and I obviously like to compare how they are doing against each other. They aren’t in the same niche, but i still like to have a look at the ranking in Alexa vs the traffic I get. The past few weeks confirmed what I thought: Alexa is not accurate. For example, let’s take one of my older website which actually receive 50x more visitors than SEO Horror. Yes, you read correctly, 50 times more visitors daily than SEO Horror, so it’s interesting to have look at the rankings!

here’s how seohorror.com looks in Alexa:

Wow that’s not bad for a website about a month old. We have to look at the 1 week average because the 3 months average isn’t really any good for me now as seohorror.com has only been live for a month or so. I’ve had a couple of days in the top 100 and now it looks like I’m mostly between 100,000 and 150,000 on a constant basis. I’m OK with that.

Now, let’s see how my other website with 50 times more traffic than SEO Horror compare:

What’s that? I’m ranked 556,812 this week! I mean, 50 times more traffic and I’m poorly ranked. You see how inaccurate it is!

Why does it look so inaccurate?

The reason it looks so inaccurate between my two websites is because they aren’t in the same niche. The visitors at SEO Horror are SEO/Web marketers and there are good chances you guys use the Alexa toolbar. If 50% of my readers use the Alexa Toolbar, it will certainly boost my rankings because a normal percentage could be something like 0.5% of the readers. Now, on my other blog, which is definitely not aimed at techies, nobody uses the Alexa toolbar and nobody has a single clue what this toolbar is all about. So even if I receive 50 times more traffic, because nobody use the toolbar, I get a poor ranking.

Is it any good then?

It’s good to compare with websites within your niche. For example, if I compare my blog with another SEO blog, then it makes a little more sense when I look at the numbers. If I take a look at a cooking recipe website, then it doesn’t make any sense to compare. Alexa is mainly used as a traffic estimate and to put a price on how much you’ll sell advertisement on your website. If your Alexa ranking is good, you can usually sell advertisement a little more, especially if you’re in the top 100. So, the bottom line is that it’s so much easier to get a good ranking in Alexa with a tech/SEO/internet marketing blog!

So, you can continue to use Alexa to check your website progression, but it’s definitely not everything as you just saw. 50 times more traffic does not mean 50 times better ranking….In fact it can be the complete opposite as you just saw!