Advanced Web Metrics

When viewing Google Analytics reports, I constantly need to remind myself of the difference between goals and conversions (may be its just me that gets confused..!). Whatever, I thought I would share my clarification.

One obvious difference is that a transaction is associated with an e-commerce completion (a purchase) while a goal conversion is considered a non-ecommerce conversion, such as a PDF download, a form completion or visit to a special offers page. Of course they are all conversions, which is where I think confusion lies.

Explanation: The most important difference as far as Google Analytics is concerned, is that a conversion can only happen once during a visitor session - that is, a visitor can only become a customer (convert) once and that makes sense. However, if one of your goals is set to *.pdf for example (any PDF file download), then should a visitor download 5 PDF files during their session, it will only show as one conversion in your Goal Conversion reports. Assuming you are tracking pdf downloads, the 5 PDF files will of course show in your Content > Top Content report.

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Keeping a local copy of your Google Analytics data can be very useful for your organisation. For example, Google currently commits to keeping GA data for 25 months allowing you to compare year on year reports. That is adequate for most users, but what if you wish to go further back? Wouldn’t it be useful to retain a local copy of the collected data?

Benefits of keeping a local copy of GA visitor data

What you can do with your local copy of your data:

1. Greater control over your data
2. Troubleshoot GA implementation issues
3. Process historical data as far back as you wish - using Urchin
4. Re-process data when you wish - using Urchin

The simple way to keep a local copy, is to use the _userv variable in your Google Analytics Tracking Code (GATC) as follows:

_userv=2;

By setting this variable, GA visitor data is simultaneously streamed to your web server logfiles in addition to being sent to Google Analytics for processing. A complete GATC to backup your GA data locally would look something like this:

<script src="http://www.google-analytics.com/urchin.js" type="text/javascript"></script>
<script type="text/javascript">
 _uacct = "UA-XXXXX-1";
 var _userv=2;
 urchinTracker();
</script>

This is simple to achieve as all web servers log their activity by default, usually in plain text format. Once implemented, open your logfiles to verify the presence of additional utm.gif entries that correspond to the visit data as ’seen’ by Google Analytics.

A typical Apache logfile line entry (line wrapped here) looks like this:

86.138.209.96 www.mysite.com - [01/Oct/2007:03:34:02 +0100] "GET /__utm.gif?utmwv=1&utmt=var&utmn=

2108116629 HTTP/1.1" 200 35 "http://www.mysite.com/pageX.htm" "Mozilla/4.0 (compatible; MSIE 6.0;

Windows NT 5.1; SV1; .NET CLR 1.1.4322)" "__utma=1.117971038.1175394730.1175394730.1175394730.1;

__utmb=1; __utmc=1; __utmz=1.1175394730.1.1.utmcid=23|utmgclid=CP-Bssq-oIsCFQMrlAodeUThgA|

utmccn=(not+set)|utmcmd=(not+set)|utmctr=looking+for+site; __utmv=1.Section One"

[GA-Experts.co.uk has a best practice guide on configuring an Apache logfile format]

For Microsoft IIS, the format (line wrapped) can be as follows:

2007-10-01 01:56:56 68.222.73.77 - - GET /__utm.gif utmn=1395285084&utmsr=1280x1024&utmsa=1280x960

&utmsc=32-bit&utmbs=1280x809&utmul=en-us&utmje=1&utmce=1&utmtz=-0500&utmjv=1.3&utmcn=1&utmr

=http://www.yoursite.com/s/s.dll?spage=search%2Fresultshome1.htm&startdate=01%2F01%2F2010&

man=1&num=10&SearchType=web&string=looking+for+mysite.com&imageField.x=12&imageField.y=6&utmp

=/ 200 878 853 93 - - Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.1;+SV1;+.NET+CLR+1.0.3705;

+Media+Center+PC+3.1;+.NET+CLR+1.1.4322) - http://www.yoursite.com/

In both examples, the augmented information applied by the GATC is the addition of utmX name value pairs. This is known as HYBRID data collection - the benefits of which are discussed in the post Software v Page Tags v HYBRIDS.

The benefits explained in detail

1. Greater control over your data
Some organisations simply feel more comfortable having their data sitting physically within their premises and are prepared to invest in the IT resources to do so. Of course you can not simply run this data through an alternative web analytics vendor, as the GATC page tag information will be meaningless to anyone else. However, it does give you the option of passing your data to a 3rd party auditing service such as ABCE. Audit companies are used to verify web site visitor numbers - useful for content publishing sites that sell advertising and therefore wish to validate their rate cards.

NOTE: Be aware that when doing this, protecting end-user privacy (your visitors) is your responsibility and you should be transparent about this in your privacy policy.

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Urchin is the software company and technology that Google acquired in April 2005 that went on to become Google Analytics. Urchin is a downloadable software tool that runs on a local server (Unix and Windows) providing web analytics reports by processing web server logfiles - including HYBRID logfiles - which are the most accurate. Although not as feature rich as GA, Urchin is essentially the same technology that allows you to view historical data over any time period you have data for, as well as providing complimentary information not available in GA.

Data available in the latest Urchin beta release that GA does not have:
(click for screenshots - opens new window)

• Error page/Status code reports
• Bandwidth reports
• Login name reports - standard Apache .htaccess or any authentication that logs usernames in the logfile
• Visitor history report - tracking individual visitors (anonymously)
• Greater customisation - show as much or as little data as you want
• Data is stored locally on your server in a mysql database - allows for ad-hoc data queries

Reporting differences between GA and Urchin beta software:

• GA imports AdWords cost data with little fuss
  Just just two tick boxes to click and the data is collected daily. For Urchin, this is a manual process
• The GA dashboard is fully customisable
  With up to 12 different reports that can be changed and re-ordered on a per user basis. Urchin summary dashboards are fixed
• GA geographic overlay is best in class
  With zoom and continent/subcontinent breakdown, this GA report is one of the best out there. Urchin geographic overlay is a little more basic (same as GA v1.0), though still very good
• GA is available in 25 languages, Urchin is available in 12
• GA has internal site search reports, Urchin does not
• GA has event tracking (beta), Urchin does not

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My colleague Avinash recently presented at SES San Jose his thoughts on the current vendor space including: Visual Sciences, Omniture, IndexTools, Clicktracks, WebTrends and Google Analytics. As always, his talks are very engaging and thought provoking. For me though, one slide really stood out - the idea that a HYBRID web analytics tool can’t hunt - you need to view his presentation to follow that, but essentially the analogy is that HYBRIDs are not good as a web analytics tool. As Avinash knows, I disagree with this point of view, so I wanted to explain why here.

By HYBRID tool, what is generally meant is the combination of the page tagging technique combined with logfile data to produce cookie fortified logfiles. This was discussed in a white paper before I joined Google - Web Analytics Data Sources. There are significant advantages to doing this as shown in the diagram below. Essentially a hybrid allows you combine the benefits of both techniques to give you the most complete picture of visitor activity on your web site.

Key HYBRID benefits over and above a page tag only system include:

• You own the collected data in the most direct sense of the word and can therefore reprocess it at will
• Being able to track search engine robot activity
• All downloaded files are tracked automatically without any modification of page html content
• Partial file downloads can be tracked e.g. partial views of PDF files
• Error pages can be tracked automatically without any modification of page html content

So a HYBRID technique offers real benefits. However, “with such great power comes great responsibility” (Spiderman!) which for a HYBRID web analytics tool means you take responsibility for:

• Applying HYBRID software updates
• Archiving and compressing your logfiles (which get very large very quickly)
• Protecting end-user privacy - you have a legal responsibility to protect the privacy of your visitors and store logfile data securely.

HYBRIDS require a significant IT investment to run smoothly, which many organisations struggle to justify - hence the proliferation of page tag technique adoptions. Nonetheless, a HYBRID method remains an effective technique for improving the accuracy of either a page tag or logfile solution.

Are you using (or have used) a HYBRID method or perhaps some other technique to improve accuracy? Share your thoughts with a comment.

My standard word of caution - This is a tech tip and requires you to have a knowledge of html and javascript to implement and use it…

Following on from my previous post Tracking banners and other outgoing links automatically, this GA hack allows you to track downloads automatically. As you may know, tracking download files such as PDF, EXE, DOC and XLS can be achieved quite easily with the modification of the link to include an urchinTracker call to log a virtual pageview. However, as for tracking outgoing links, manually modifying each download link becomes inefficient when there are large numbers of ever changing files to track. You can overcome this by applying the JavaScript code below:

<script type="text/JavaScript">
// Only links written to the page (already in the DOM) will be tagged
// Script can be called multiple times

function addExtDocEvents() {
var as = document.getElementsByTagName("a");
var extDoc = [".doc",".xls",".exe",".zip",".pdf",".js"];
// add further document types as required

for(var i=0; i<as.length; i++) {
	var tmp = as[i].getAttribute("onclick");

// Tracking electronic documents - doc, xls, pdf, exe, zip
if (tmp != null && tmp.indexOf('urchinTracker') > -1) continue;
for (var j=0; j<extDoc.length; j++) {
if (as[i].href.indexOf(extTrack[0]) != -1 &&
as[i].href.indexOf(extDoc[j]) != -1) {
		var splitResult = as[i].href.split(extTrack[0]);
		as[i].setAttribute("onclick",((tmp != null) ? tmp : "") +
			"urchinTracker('/downloads" +splitResult[1]+ "');");
		break;
	}
}
}
}
addExtDocEvents()
</script>

The script works by looking for links within the browser’s Document Object Model (DOM) that match the file extension given in the variable array extDoc. If so it is modified to include the urchinTracker call. By this method, all file downloads will be reported as:

/downloads/the-url-that-is-clicked-on

Where the-url-that-is-on clicked on is minus ‘http://’. You can modify the JavaScript to adjust the path as required,

Tip: As for the Tracking of banners and other outgoing links, the position of this code within your page is important. This must placed after your call to the GATC. Alternatively place the addExtDocEvents() call in an onLoad event handler and host the JavaScript in a separate file.

A note on performance: Each time your page loads, this script will go through all links referenced on the page to see if it is for a download. Clearly the more links on your page, the harder the script must work. As long as the number of links on each page number in the hundreds and not thousands, performance should not be a problem. Also, pages with a large number of links, it is possible that visitors will click on a download link before the script has modified it. The result is that click through will not be tracked by Google Analytics.

I have combined both the Tracking of banners and other outgoing links - automatically with this hack into a single script that is available at: http://www.advanced-web-metrics.com/blog/scripts.

Did you find this tip useful? All tips are being grouped under the category GA Hacks. Please provide your feedback with a comment.