I am pleased to announce that we have a new author for EasyList, EasyPrivacy and EasyList Germany: Famlam. He has been a member of the EasyList forum for nearly a year and a half and is already a contributor to AdBlock for Chrome, one of several advert blocking add-ons for Chrome that use the EasyList subscriptions. He was officially granted the status of EasyList author yesterday evening and I hope that you will welcome him into his new role.

I would also encourage anyone else interested in becoming an author for EasyList, EasyPrivacy or EasyList Germany to contact the project. As I noted in a recent article on EasyList usage and downloads, we have very few authors relative to the millions of users of the subscriptions and would be glad of additional assistance.

Looking back, it has been a long time since anyone has evaluated or released the statistics for the EasyList subscriptions, so I thought that, as August has just eneded, it might be time to estimate exactly how many users there are of the filter lists.

Even though I am aware that most people are interested simply in the user estimates, I should start by explaining how the statistics are gathered for the users of EasyPrivacy and any other privacy conscious individuals. When a browser connects to a web server, it automatically sends information to request a copy of, in this instance, a text file. This request includes the user agent, which for Firefox states the name of the operating system (although this information is not present in my statistics) and the version of the browser. The Adblock Plus website, like so many others, logs these requests with the time and date the request was made. These logs are then analysed by AWStats. No active tracking scripts have been installed.

Although there is a lot of information, calculating the number of users of the EasyList subscriptions cannot provide a complete picture for a variety of reasons. Adblock Plus updates subscriptions between four and six days after they were last updated. However, if a user does not use a browser for a day, then an update will be delayed for a day, up to ten days after a subscription was last updated. This being August, many people are likely to be on holiday, which means that the subscription updates are likely to be less frequent than my assumed value of five days. It is also possible, but extremely unlikely, that results may be overestimated as a result of many people forcing a download from the Adblock Plus preferences window.

Viewing the statistics at the time this algorithm was implemented, Wladimir hoped that the changes would prevent a “Monday peak” from overloading the server, the result of office workers all updating on Monday morning if the five day interval passed over the weekend. However, it is clear that there are a number of users of the subscriptions who do not have a recent version of Adblock Plus installed. Using the four full weeks of August 2011 as an example, Mondays show on average 12% more downloads than would be expected (week total / 7), ranging from 110.8% to 118.5% of the expected traffic. In contrast, downloads tended to tail off as the week progressed, the most marked drop being on Saturdays and Sundays, with an average of 92% of the expected traffic each day. This ranged from a low of 91.6% on Saturday 13 August to a weekend high of 95.8% on Sunday 28 August.

In spite of the variation based on week day the total number of downloads per week was fairly stable: in order, each week achieved 98.1%, 99.0%, 100.7% and 102.2% of expected traffic, the initial low results likely the results of holidays without computers and therefore without updates to EasyList.

Now, however, it is time to answer the big question: how many people actually use the subscriptions? These values were calculated by taking the total number of downloads in a month, dividing the resulting total by thirty one to find the average number per day and then multiplying by five, as this would be, if everyone used their browser daily (which they don't), the average update period.

Going through the subscriptions, it is no surprise that EasyList has the largest user base. Taking into account all combined subscriptions, versions and variations, such as the one with element hiding rules, the one without rules for adult websites and relevant tracking protection lists, we find that there were seventy three million downloads of the file in August, suggesting that there are twelve million users, of whom 99% use Adblock Plus filter format. EasyList Germany has also been popular, with two and a half million users (99.9% Adblock Plus format), as has EasyPrivacy, despite the comparatively paltry total of "just" half a million users. However, unlike EasyList and EasyList Germany, which have seen little usage as Tracking Protection Lists, just over half of the users of EasyPrivacy use EasyPrivacy TPL, its popularity likely due to Microsoft's promotion of the list, which we are very grateful for.

Next, it is possible to put these values in perspective: how dominant is EasyList as an Adblock Plus subscription? Looking at the public statistics page for the add-on and ignoring the recent erroneous readings, we find that there are twelve and a half million users of Adblock Plus. Taking into account the usage of AdBlock for Chrome and Adblock Plus for Chrome, which according to user agents accounts for, at most, 15% of installations, we find that 80% of people using Adblock Plus use EasyList as a primary subscription. This is despite the random selection of EasyList or Fanboy's List for a new English language user. I would attribute this popularity to historical reasons (people installed Adblock Plus when EasyList was the only recommended subscription for English language users); the large number of recommended supplementary subscriptions, including EasyList Germany, RU AdList, Liste FR and ChinaList [*], to name but a few, which are selected automatically when the subscription and browser languages match; and its position as a fallback subscription: if the browser language does not match any recommended subscription, EasyList is automatically installed.

Of course, the minor subscriptions also deserve a mention. EasyList without element hiding has accumulated around seven thousand users, EasyList without rules for adult sites has over two thousand users and EasyPrivacy without international filters has just over one thousand users. Finally, EasyTest, an EasyList supplement used for examining filters known to cause problems on websites, has accumulated just 33 users.

While there is great variation in the usage of the EasyList subscriptions, the statistics emphasise the great responsibility that we authors have - a minor mistake can quickly affect thousands of people. I would therefore appeal to anyone who has made it to the final paragraph to consider getting involved with the project to assist the very few authors we have - even suggesting rules for problematic sites helps us to reduce the time it takes to commit a fix. Regardless of this challenge, I am optimistic: provided the requisite bandwidth is made available (4.2 TB was required this month for the Adblock Plus version of EasyList alone), I see no reason why the project should not continue to be successful.

The introduction of the Adblock Plus issue reporter has resulted in a significant increase in the number of users who have reported missing adverts or problems on adult domains. These reports have often been met with little to no response for the simple reason that EasyList and EasyPrivacy policy dictates that adult domains are not considered when adding filters to the subscriptions. Adult domains have a purportedly more aggressive style of advertising than most websites, which would mean that an exceptionally high number of specific filters would be required to remove the unwanted content from domains of this nature. These filters provide little benefit to the majority of users, who would still have to regularly download the larger subscriptions despite never using the rules.

I would therefore recommend that users who regularly visit adult websites install a supplementary subscription that specifically targets domains of this nature, such as Fanboy's Adult/Dating List or the Adversity Adult List, both of which are listed in the full list of subscriptions, and report any issues that arise to the respective maintainers.

Update: 30/05/2011

Subscription policy on adult websites has been revised; the changes and the reasons for the alterations are explained in a more recent article.

If users should encounter unwanted items when using Adblock Plus it is extremely easy to report and resolve the issue with the assistance of the community.

The first recommended response is to update all subscriptions used, which may be accomplished by right-clicking the Adblock Plus logo in the top right-hand corner of the browser, selecting "Preferences..." and then activating the "Filters" menu followed by the option "Update all subscriptions". If there are no subscriptions installed, then users are strongly advised to select one; a full list of possibilities is available at the Adblock Plus website. The problematic page should then be loaded or refreshed. If the issue is resolved as a result of this command it means that the authors are already aware of the content encountered and have updated the subscription to match.

If the unwanted content remains, it is advisable to submit a report directly to the authors about the encountered item, as this will ensure that the issue is resolved for all users of the subscription and that any additional assistance necessary may be easily provided by the community. It is also hassle-free, as both the EasyList and Adblock Plus forums do not require registration to post, and there is the additional option of contacting the EasyList authors via e-mail.

There are, however, crucial pieces of information that are needed to quickly and effectively deal with the suggestions; these are listed below in order of priority. Too much data is always preferable to too little; authors may not receive the same content because of geographical restrictions, and it is therefore beneficial to have all the information about the unwanted content provided as opposed to having to enquire further about specific aspects of the issue.

1. A specific link to the problematic page

   The critical bit of information that is required in a report is the address of the website that is affected, as this allows authors to personally examine the page and attempt to reproduce the issue. It is also important that this link is as specific as possible and points to the exact location where filters are needed, as this prevents authors from needlessly exploring domains in the hope that they can locate the subject of the report. In many instances a specific link to a problematic page is all that is required to resolve an issue.

2. Addresses of the unwanted items

   Adblock Plus and other similar pieces of software remove unwanted items by checking whether the location of an item matches the list of forbidden content dictated by the subscription. It is therefore easier to add filters if the exact addresses are provided by the reporter. The items are listed in the Adblock Plus blockable items window, which may be opened by right-clicking the icon in the top left-hand corner of the browser and selecting the menu option "Open blockable items". If the exact reference to the content cannot be discerned, then selecting everything listed and copying it into a report is more useful than having no information about the addresses.

3. The location of the unwanted content

   Sometimes even a specific link to a page is not enough to find the unwanted content, and it is therefore advisable that reports either explain where it is or provide a screenshot demonstrating the location. This is especially useful if there are unblocked text adverts, as they will not be listed as blockable items because they are a part of the page.

4. Custom filters

   If any rules have been created that successfully remove some or all of the unwanted content from the page it is always beneficial if suggested strings are provided; however, as it is possible that an author may choose to filter content in a slightly different manner to that proposed the full addresses of unwanted content are usually more useful.

5. System information

   Occasionally, issues may arise as a result of a unique set-up. It is therefore beneficial if the following information is provided in the report:

   • Active subscription names

   • Adblock Plus version or equivalent

   • Browser name and version

Finally, it is important that users are available to answer any queries or to clarify aspects of the account. If an issue cannot be replicated then it is possible that all the work put into a report will be wasted because the person experiencing the issue is unavailable.