This is a topic of much frustration for many people. I wrote a post on this some years ago, which Google actually used for some time in their official help pages, but it is still something that we get asked regularly, so I thought it would be worth revisiting. The most common reasons for discrepancies between AdWords and Analytics data and how you can further avoid confusion are as follows:
1. Clicks vs. Visits Discrepancies
Clicks represent the actual number of clicks that you paid for and the number of clicks your campaign ad actually received. It is normal for click and visit numbers to vary, as visitors sometimes click PPC ads in their first session and then re-visit the site in later sessions from other sources – e.g. directly by typing the address into their browser, resulting in 1 click and several visits, as the referral data from the original visit was retained.
If the situation is reversed, and you have fewer visits than you have clicks, there may well be a tracking issue involved, i.e. Analytics tracking code may not be added to every page on your website.
Pro tip: Use a free tool such as Screaming Frog to do the legwork and check for you!
2. Invalid Clicks
Invalid clicks are not charged clicks and occur when a user repeatedly clicks an ad, either to inflate your costs or click-through rate The AdWords system automatically filters out invalid clicks from its reports, whilst Google Analytics will still report the visits to your website from any invalid clicks.
3. Auto-tagging in your AdWords account
Have you enabled auto-tagging within the ‘My Account’ tab of your AdWords account? If so, be sure do not to disable this unless you have manually tagged your URLs with campaign tracking variables. If you accidentally disabled autotagging, or fail to tag your URLs correctly, the visit will not be recognised as cost per click (CPC) traffic from paid search campaigns in Analytics, but will instead be attributed to Google organic traffic.
Pro tip: If you’re looking for help with manually tracking your campaign variables, use the Free ‘URL builder’ tool, available here.
4. Landing Page Tracking
Is the landing page that you are using for your destination URL tracking in Analytics? If not, your campaign information (google click id, etc.) will not be passed to Google Analytics. Make sure that you have the relevant tracking code present on all on your landing pages. See the Pro Tip in point 1 to help you check your code installation.
5. Landing Page Loading
Lastly, If your landing page is redirecting to a different page, the Analytics code can be obstructed from executing, and as such it may not identify the visit as coming from PPC activity. So, be careful with 301 or 302 redirects, as the campaign tracking variables will be lost when a URL redirects!