When it comes to marketing everyone is out to compose the most compelling message possible and then measure an audience's reaction to that message. The question then becomes are measuring the tools that web marketers use reliable? I think the general consensus is that many of the tools that rely on Java Script are less reliable than marketers would like them to be.
Stone Temple Consulting has performed a quality test showing that where one locates the Java Script that our analytics tools rely on matters. The two things that the test showed were one that page load time matters and two that the amount traffic to a server can adversely affect page load time. They had to take both of these concepts into account when performing their test.
Their test for all intensive purposes showed the effects of having Java Script located at the top of a web page and that of the same script located at the bottom of the page. Their conclusions seem to be logical but are well worth reviewing, especially in relation to your own websites performance.
Our suggestion would be that if your page load is normally pretty snappy (total page load time of under 3 or 4 seconds), then keep your Javascript at the bottom, and remove any risk related to analytics vendor downtime. The small loss of data you see in this scenario should not be a significant factor in the value of your analytics data.
But, if your page load time is a bit slower (4 seconds or more), you may want to consider placing your analytics Javascript at the top of your web page. Your data loss will be larger, and also the nature of the lost data may start to differ.
Test like these reminder marketers why it is important to consider running two different analytics solutions in parallel. Examine the statistical differences of the same data over a period of days, weeks, and months and then watch to see if the reporting trends hold true. Actually attempting to reconcile data is nightmare and probably something you don't want to do because the numbers are never going to match 100%, as there are still some basic flaws with any form of analytics acquisition on the web.
So my question for the readers of this blog is how much do you trust the analytics data you are reviewing on your own sites? Does this type of test make you want to reconsider the load times of your site as well as the position of the Java Script on your site?
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