Why do Google Webmaster Tools and Google Analytics Stats Differ?
So, lucky us, April 14th 2010, Google announces ‘More data and Charts in Top Search Queries’ using Google Webmaster Tools . Where previously, Google Webmaster Tools reported the average position for each Google search query, you can now click on the query to retrieve ‘actual’ data including:
1. Number of Impressions (How many times your site appeared in SERPS based on the search query)
2. Position in SERPS (What position your site appeared in SERPS when a search on the query was made)
3. Number of Clickthroughs (How many times your site link was clicked from SERPS)
4. Percentage of Clickthroughs (What percentage of all clicks to your site did this query represent?)
5. The actual pages that appeared in SERPS
Google Webmaster Tools is based on crawl data (Google ‘pulls’ the data when it pleases) whereas Google Analytics is based on data being sent to Google when a visitor arrives at your site and views each page or specific page elements (Your site ‘pushes’ the data). This can result in a lag in time for data appearing in Google Webmaster Tools as although GWT will have the data for visits as soon as they happen, they may not publish them until they crawl your site.
- Google Webmaster Tools does some additional data processing e.g. to remove duplicates and visits from robots.
Add to this that the way that traffic sources and sessions are collected by varying tools. In Google Analytics, a session is 30 minutes. If a visitor;
1. Arrives at a site using Google Search
2. Stays on site for 5 minutes
3. Leaves and goes back to Google SERPS
4. Comes back to site via Google SERPS 30 seconds later
The session length will still be under 30 minutes and therefore will presumably count as;
1. 2 visits via 2 search queries in Google WMT
2. 1 visit via 1 search query in Google Analytics
Throw in the fact that we are never completely sure what Google Webmaster Tools is including (e.g. in terms of Universal Search Google properties), then comparing the data is like comparing apples to bananas.
The bottom line is to remember that any stats tool is really there to monitor cause and effect in terms of trends. Worry more if you increase position in SERPS using Webmaster Tools for a search query (e.g. by changing the title) and if your bounce rate then increases for that term in Google Analytics as this is real cause and effect monitoring. Worry less about the fact that visits are calculated in different ways.
Simply put – let the insight gained from one tool feed into the insight gained from another.