Unique Visitors are DIFFERENT in the Summary Stats compared to the Detailed Log Stats - what's wrong?
First, it's important to be clear on the definition of Unique Visitor. A Unique Visitor is a "distinct" or "separate" visitor.
In your summary stats for today, for example, you may have 25 Pageloads and 4 Unique Visitors. This means that 4 different/distinct/separate visitors looked at a combined total of 25 pages on your site.
Summary Stats - How Uniques are Calculated
In the Summary Stats, Unique Visitors are calculated by the use of a "cookie". A "cookie" is a small text file that we use at StatCounter to determine whether a visitor has been to your site in the recent past.
When a visitor first looks at a page on your site, a StatCounter cookie is placed in their browser (if allowed). Then, as the visitor browses your site, the cookie tells us that this is NOT a new/distinct/separate visitor visiting your site each time. Instead, it's the same visitor looking at several different pages.
You should note that it IS possible for a visitor to disable all cookies in their browser.
When a visitor has cookies disabled, we have no way of knowing if they are a unique visitor or not. If a visitor has cookies disabled, then each page of your site that he views will be considered to be a pageload by a Unique Visitor. Obviously, this is not strictly correct, but since most visitors will have cookies enabled, this does give you a fairly accurate overview of your Unique Visitors.
Stats from Detailed Log - How Uniques are Calculated
In the Detailed Log, Unique Visitors are calculated based on IP address. An IP address is a unique number assigned to a computer connected to the internet. IP addresses are generally assigned by your ISP or internet service provider. IP addresses can be static i.e. they never change - every time you connect to the internet you connect using the same IP address. OR IP addresses can be dynamic - this means that your IP address changes every time you reconnect to the internet, or in some cases while you are connected to the internet.
When a visitor first looks at a page on your site, StatCounter records the visitor's IP address. Then, as the visitor browses your site, the IP address tells us that this is not a new/distinct/separate visitor visiting your site each time. Instead, it's the same visitor looking at several different pages.
You should note, however, that in some cases a user's IP address changes each time they visit a different page of your site. (e.g. AOL users or anyone using a Dynamic Web Proxy.)
When a visitor's IP address changes constantly, we can't correctly track them as a unique visitor. Since each pageload on your site can be linked to a different IP address, each page of your site will be considered to be a pageload by a Unique Visitor. Obviously, this is not strictly correct, but since most visitors do not have a constantly changing IP address, the stat is a very good approximation of reality.
Difference in Calculation of Unique Visitors
There are positives and negatives to both of the above methods of calculating Unique Visitors. We provide you with the two different option so that you get the best possible overview of your true Unique Visitor numbers.
Summary Stats show more Unique Visitors - why?!
If a visitor has a static (unchanging) IP address BUT has cookies disabled in their browser, then the Unique Visitor count per the Summary Stats will be inflated.
As cookies are disabled, the Summary Stats will consider each pageload to be a pageload by a Unique Visitor BUT the detailed log stats will correctly capture the Unique Visitor on the basis of their IP address.
Detailed Log Stats show more Unique Visitors - why?!
If a visitor has cookies enabled, but has a constantly changing IP address, then the Unique Visitor count per the Detailed Log Stats will be inflated.
As the IP address changes with every pageload, the Detailed Log Stats consider each pageload to be a pageload by a Unique Visitor BUT the Summary Stats will correctly capture the Unique Visitor on the basis of the cookie in their browser.