
How Unique Is A Unique Visitor? - alexandros
http://www.avc.com/a_vc/2010/02/how-unique-is-a-unique-visitor.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+AVc+%28A+VC%29&utm_content=Google+Reader
======
stingraycharles
_And what they found was that a "reliable cookie" overstates user counts 2 to
4 times. That's right, if your analytics software uses cookies, it is possible
that your unique visitor counts are 2 to 4 times too high._

I wonder what their methods for determining this is. Do they mean that an
average user clears their cookies 2 to 4 times within a typical reporting
period (unlikely)? Do they mean that an average user uses 2 to 4 different
browsers to access the same site (unlikely)? Or do they mean that the average
user accesses the same websites from 2 to 4 different computers (more likely)?

These kind of claims don't mean anything if you don't know how to interpret
it. People know how to interpret unique visitors: it essentially means "unique
browser sessions", and most people that are serious about analytics are aware
of this. But don't start dividing the unique visitors by 2 to 4 yet, if you
don't know what the resulting number exactly represents.

(disclaimer: I'm a service provider in online ads and biased too)

~~~
FluidDjango
Correct me as needed, but I took OP to regard "unique visitor" as meaning
"unique visiting person" - and to be citing himself as overcounted when he
visited a site variously via Safari, FF, Chrome, and iPhone - which certainly
happens to me many days.

------
apowell
Tracking uniques with Flash cookies rather than browser cookies (when
possible) should compensate for the one-user-many-browsers problem. I know
there are ways for individual users to clear Flash cookies, but I don't
believe this is being done on a scale wide enough to be statistically
significant.

~~~
InclinedPlane
That sounds a lot like trying to solve a small problem by creating an even
larger problem.

Translation: whatever the problem, it's unlikely the solution is using more
Flash on your website.

------
dirtbox
Half the "unique hits" on my old Blogger are me.

------
DougWebb
It sounds like some javascript was used to hash some things like installed
plugins that vary from user to user and browser install to browser install in
order to create a more unique and reliable identifier than cookies. I'm not
sure how that can capture use of multiple browsers though.

~~~
jgrahamc
If they are on the same machine you can just use Flash cookies since there is
a single Flash cookie jar for the entire machine (across browsers).

