There are 2 main reasons why many marketers use Google Analytics filters - they help exclude traffic from internal IP's of the company and get rid of analytics spam. But filters are here not just for these 2 applications. There are actually much more cases, where filters are extremely useful.
Filters allow you to limit and modify data before adding it to the view. And that "before adding" is very important to remember. Once you apply a filter to a view, you apply it to actual data, meaning that this is irrevocable. That is actually how filters differ from segments. Latter help you modify reports, but not the data itself.
If you haven't used Google Analytics filters a lot, I recommend having a separate view (let's call it "sandbox"). In this sandbox view you can play around with filters before applying them to your main view, to be sure that they work exactly how you expected and not to destroy your data. It is easy: create a filter in sandbox view, check statistics in this view for 2-3 next days and if everything is fine, create same filter in your main view.
Filters are applied to specific views, but to be able to add/edit filters you have to have account level edit-access.
Here are some useful applications of Google Analytics filters (right now, there is a how to only for one of them - check-out the link below; but I will add how-to’s for others soon - sign-up for my newsletter to be the first to know about them).
1. Referral spam prevention filter. Referral spam has become a headache for marketers lately. Using filters you can easily get rid of this type of spam.
2. Excluding internal IP's traffic from your reports. If your site is being used extensively by colleagues or your team, it makes sense excluding their visits from your reports (as they will probably be more engaged with the site as your average user, thus skewing your data).
3. Showing full URL in reports. By default, when you look at content reports in Google Analytics, you see only path part of URL's (like /google-analytics-explained/filters/). Sometimes, especially if you are using several domains/subdomains for your site, it is very useful to see full URL's (likestony.me/google-analytics-explained/filters/). Filters will help you achieve this.
4. Solving multiple index pages problem. Sometimes you may have several URL’s for your index page (like /, /index.php, /home, etc.) In this case you will see all of them separately in the reports, making it a bit difficult to see overall statistics for the home page. Though this issue is also not very good for SEO of your site, so it is better to solve it making redirects, it may be easier to fix this issue using filters rather than waiting for your developers.
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