EU and US JavaScript Disabled Index numbers + Web Analytics data collection impact
I had a great chat (as always) with Eric Enge about a set of web analytics research numbers of his; where part of the dialogue kept coming back to elements of JavaScript being Enabled or Disabled. During the chat I promised that we would do a cross analysis among a larger set of visits (not visitors), for us to get a decent attitude on what the JavaScript Disabled index number should be.
The whole reason that this might be of interest is; that most users of Web Analytics enterprise systems today deploy a page tagging solution such as Omniture or IndexTools – where the data collection methodology is in part based on a small JavaScript. It is therefore very likely that there will be a discrepancy in the collected data if you have visitors who have disabled JavaScript. Before concluding on the impact of this understood discrepancy, let me present the results:
JavaScript Disabled Index numbers
EU: 1.4%
US: 3.05%
Source: 1.000.000.000 visits across multiple industry web properties using IndexTools.
(VisualRevenue.com/blog – Dennis R. Mortensen)
Where one might, at first sight, be concerned about a 2% to 3% discrepancy, due to the fact that JavaScript is not enabled. This is normal and it is very common that people confuses or transmit to much value to JavaScript disabled numbers as they either expect NO data collection at all or very limited data collection. The fact is that most (all the ones I know) of the enterprise vendors have a noscript IMAGE “fall-back” data collection methodology – meaning that all of those who have JavaScript disabled will be tracked!
It is however valid to say that the IMAGE fall-back methodology do not have the same degree of nuance (the number of metrics) as the original intended JavaScript. But all the basic information is collected and tied together in a session. You might (dependant on your Web Analytics solution) even be able to configure the fall-back methodology to track custom actions, revenue and other information.
Therefore and as example, if we say you have a cool 4% sales conversion rate on your US visitors, the discrepancy in your Revenue Metric (KPI) should not be off more than 3.05% of your 4% and thus you cannot attribute JavaScript Disabled discrepancy to more than 0.12% of your Revenue Metric. On $1,000,000 in sales, that is only $1,220 – AND some vendors even give you an opportunity to track those last $1,220 as well :-)
Conclusion:
It is very likely for us to believe that we will see a continuous decline in visitors who have JavaScript Disabled and it is very fair to trust that visitors with JavaScript Disabled have little or no impact on your web analysis efforts. However; it is a fact that data might not be 100% accurate due to this data collection defect, but the impact is much smaller than the immediate believed 2% to 3% as first assumed.
So what are your JavaScript Disabled numbers; are they close to my index numbers or… am I completely off? :-)
Comments please. (especially if you have some RAW numbers on IMAGE disabled)
N.B.
I checked my blog and by pure luck, the JavaScript Disabled number for US visitors matched the Index Number almost spot on.
August 18th, 2007 at 18:13
Very insightful post. There is always so much worry about JavaScript or cookies being disabled, but once you understand what’s going on, once you can “make a good story” to explain it, it’s no SO bad. In fact, while it is frequent to have informational areas of a site working without JavaScript, more and more transactions requires JavaScript to be enabled. It might be important to do a thorough analysis to see if those 3% or 4% of visits are really, indeed, your target customers and if they convert.
August 18th, 2007 at 18:36
Hi Stéphane,
See, this is a perfect add-on to the post. As I (like you) to some extent believe (or at least believe it to be researched) that those who in fact disable e.g. Java Script or other key browser functionality – might not even be part of your target audience (those who convert) – which leads my suggested example 0.12% discrepancy being a WORST CASE scenario!
Great comment. Thanks.
See you at Emetrics Washington!?
Dennis :-)
August 18th, 2007 at 23:53
>>
I checked my blog and by pure luck..
>>
Pure luck or…. some clever cooking for the numbers!!! :)
Just kidding.
This is a great post Dennis (insert everything Mr. Hamel said above).
See you in a couple days.
-Avinash.
August 19th, 2007 at 9:47
Hi Avinash,
He he… Me and Gordon Ramsay are cooking nothing but delightful numbers :-)
See you shortly.
Dennis.
June 2nd, 2009 at 6:08
[...] is that the percentage of JS disabled browsers is very close to the IE6 market share. Back in 2007, 3.05% of the browsers located in US were JS disabled; ever since there, the percent must have been [...]
February 18th, 2010 at 9:21
Hello Dennis,
Do you know if there is any discrepancy introduced by the use of noscript image “fallback” solution, since these images might be requested by a number of robots? (although most common robots such as googlebots ignore them).
Sorry to comment on an old post but I searched information about this issue and stumbled upon your blog, which is by the way very interesting.
February 19th, 2010 at 15:00
Hi Jens,
We maintained a list of robots which were excluded from the reporting. Not to say that a non-human couldn’t call the pixel – however, when that did happen, our customers typically just out-segmented that themselves.
Cheers
d. :-)
June 18th, 2010 at 7:53
Great blog, very valuable – may I ask why you say “It is very likely for us to believe that we will see a continuous decline in visitors who have JavaScript Disabled”?
June 20th, 2010 at 13:23
Hey Craig,
It very much seems like, most websites today, and most certainly tomorrow are deploying JavaScript for not only extended functionality, but for basic functionality. That being the case, I personally can’t see people disabling JavaScript anymore, than they do today, as surfing the web and using your standard services becomes difficult to the point of impossible – whether that being your Internet Bank or your favorite retailer.
Perhaps it’s time for some updated research, instead of opinion data :-)
cheers
d.