Your first thought might be to use profiles to remove your unwanted websites but we have found using aliases is much easier. The reason for this is Profiles use keyword matching and is a bit of a dark art.
Lets say you want to exclude example.com from your report.
So you create a profile called Excluded Sites and add the keyword: example.com Should be good right?
But what if there is another profile that has the keyword: ample
Which profile does example.com get included in?
Or what if the full URL is: www.example.com/naughty/sex.jpg
This would then match the adult profile as well as the previous two profiles.
You can see how profiles becomes a 'weird' place to create an exclusion list.
Not to mention the time required to add all the includes and excludes needed to ensure a hit/record is matched to the profile you require.
This is why we would recommend you use an alias instead as it is much easier and faster to setup.
How to setup your Excluded Site Domain alias;
The easiest way to filter would be to create an alias of all the site domains you do not want to report on.
1) Create an alias with the summary Site domain assigned to it called "Excluded Sites".
2) Then make a group called "SITES TO IGNORE".
3) Add group key values to the "SITES TO IGNORE" group. eg. Add the site domains that you don't want to see in your data such as www.example.com.
Once this is done you can easily apply a filter to the import, analysis, or reporting process.
Using Wildcard Matching
It is important to note that when adding group keys ("www.example.com" like in the above example) that you can also use wildcard matching. Using wildcard matching will allow you to enter *example* instead of the full site domain.
To use wildcard matching you must first make sure that "Use Wildcard Matching" is turned on for your alias.
Once this is checked it will allow you to add keys like *google* which means it will match all site domains that contain the text google. Just add a '*' to the beginning and/or end of the text you enter to use the wildcard matching.
A brief example of wildcard meanings
*google* = means match any site domains containing text "google".
google* = means match any site domains starting with the text "google".
*google = means match any site domains ending with the text "google".
It is also important to note that the disadvantage of this option is that it takes longer to match the strings to the alias groups, so any reports using this alias may take longer to generate.
Applying the alias to a filter
1) Go To the Filters tab page in the wizard (same for: Import, Summaries/Analysis, or Reports).
2) Click Add | Field value filter.
The following dialog will appear.
3) Select Site Domain as the summary;
4) Select your new alias ("Excluded Sites") as the alias.
-This will display a list of the groups you made for this alias ("SITES TO IGNORE").
5) Make sure you choose the Exclude radio box so the software knows not to import this data.
6) Select the alias group boxes you wish the filter (eg. "SITES TO IGNORE").
7) Click OK.
8) Done the filter is now setup.
Once this is setup the filtered data will be excluded from your Report, Imported data, or summary view.
Other links that may be of interest to you:
Filtering on Import