Common Reasons for Incorrect Data in Web Analytics

Incorrect data is an acute problem for online businesses. While most businesses have started to realize the importance of data-mining and performance-based marketing, it seems that some of the effort has been going in the wrong direction. The point is not about having as much data as possible, but rather having the data you can actually work with – structured, complete and correct.

Below I will outline some common sources of erroneous or incomplete data and give some advice on how to avoid the mistakes.

Unclear or imprecise definitions of KPIs.

Even if your company is not very large, make sure that everyone dealing with data understands precisely what is included in statistics and how it is calculated. It even makes sense to create a written document defining the KPIs, no matter how simple or self-explanatory they might seem.

For example, if you want to calculate CTR (click through rate) for banner advertising, which is, in essence, the number of clicks on the banner divided by the number of banner impressions, you can ask yourself a range of questions. Do you want to apply unique banner impressions and unique clicks (that is, per user)? At what intervals do you want to measure the CTR (per hour, per day, per week)? How do you go about natural fluctuations in CTR (e.g. during the day vs at night), do you want to make them part of your statistics or just ignore them and take the average? How do you group the data: by region, by traffic source, by banner type, etc.? If you run banner tests, do you want to exclude the test data from the overall statistics?

As you can see, the answers to these questions might greatly influence the outcome, i.e. the CTR your  data analyst will produce at the end of the day.

Technical issues

The more complex a system is, the more likely it is to malfunction. Always check for technical issues if dealing with data inconsistency. For this, it is best to work with statistical and technical benchmarks, based on the normal system behavior in the past.

Technical problems influencing the data consistency may, firstly, be caused by the under-performance of the system itself (for example, the banners are not served for a period of time, or are not displayed correctly in some browsers). Secondly, even if the system functions well, there might be problems in capturing or storing the data (e.g. not enough RAM to perform operations causes the database server to crash). And thirdly, if you do not query the database directly but let the data flow through a business intelligence system, there might be all kinds of compatibility problems between the systems.

Incorrect calculations

This is the least predictable source of data inaccuracy. It starts with how the data is collected and aggregated in the system. Even if one has enough clarity on how the KPIs are constructed, there is always a chance that the setup of the analytics system will divert from the desired parameters. Furthermore, if data processing and analysis are largely done manually, the probability of a mistake rises with every step. Also, merging the data from several sources can impact the data consistency in a negative way, especially if some parameters have to be converted or rounded up before the merging.

Thus, human factor should not be underestimated, and the only way to minimize the number of errors is double checking the calculations, or better still, automating as much of data processing as possible.

In conclusion, if you find that the data does not “seem right”, even after you have excluded every possibility of a mistake, you might need to look for the reason outside of your analytics system. One of my previous blog posts looks at this issue in more detail.

Share this post

Guiding the Customer: Website Conversion Optimisation

Using this advice you can optimize the performance and conversion of your website or a landing page.

The Internet is getting increasingly cluttered – thus, having your own web page does not guarantee the success of your business. Apart from attracting the traffic to your web page through advertising or SEO, boosting the conversion rates (that is, getting actual sales or having visitors perform other actions you want them to) is extremely important. Below are some areas you can use to leverage the performance of your online presence.

Landing page

Avoid using your home page as your landing page for every campaign you do. Because a visitor decides within milliseconds, whether to stay on your page or click the “Back” button in his browser, make sure that what he sees matches his current needs. Landing pages with too much information or too many functions act distracting and irritating, as the user is clicking through the areas of the web page struggling to find what he needs. Even if your website contains a lot of information and categories, try to limit the amount of information presented down to the minimum and make it easy to digest.

Websites with unusual, “creative” layouts may, on the one hand, attract the attention of the visitor, but due to the reduced usability, are very likely to decrease your conversion rates, as the website visitors (and the potential customers!) get lost in the jungle of JavaScript and Flash animations.

Another important point is the technical usability of your website, e.g. the compatibly with different browser types, the absence of broken links, and last, but not least, the speed of the website (the speed of the website is also an important factor in search engine optimization).


In order to convert, your website hast to contain clear and precise calls-to-action. Some guidelines to follow: the button should match the overall design of the website (so as not to be perceived as advertising or an external link), but on the other hand, provide a color or size contrast to the less essential areas of the web page.

The position of the clickable CTA should be within the normal eye path of the visitor: according to some experts, the location in the lower part of the page on the right-hand side is advantageous, however, this would not work for long pages, where you have to scroll or for smaller monitors (netbooks, mobile, etc). On the other hand, elements placed in the upper left hand corner often get the most initial attention by a visitor (Google golden triangle).

Conversion barriers

Some well or less well known conversion barriers include the areas of the web page requiring registration, long forms to fill out, CAPTCHAs (pictures with words or numbers you need to type in to prove your human identity), distractions in the form of cross-selling or external advertisements, extended visitor’s path (a number of clicks required to reach the intended goal) and all kinds of usability and performance problems.

Test and find out

In conclusion, it must be noted that the guidelines given above are of very general nature, in other words, only by testing and monitoring performance you can learn about the methods working in your particular case. Some testing methods are A/B tests (tests with a control group), mouse tracking and eye tracking tests, as well as thorough studying of customer segmentation and implementing methods of website optimization for different target segments.

Share this post