Wikipedia, which has been referred to as a world treasure, turns 20 on Friday. According to research conducted over the years — including a scientific study published by the journal Nature in 2005 and a report commissioned by the site's Wikimedia Foundation in 2012 — Wikipedia's entries are comparable in quality to those in prestigious encyclopedias such as Britannica. However, it is difficult to measure the consistency of information that can be altered at any time.

Sometimes, the quality of entries is a question of word count because longer articles will generally contain more details. Length, though, varies by language. For example, a sentence in French might contain more words than one in Kiswahili, which attaches subjects, objects and tenses to verbs. Measuring according to the file size of an entry is also of limited use because some alphabets take up more virtual space, Martin Rulsch, who works for the German section of Wikimedia and has volunteered for the site in various capacities for over 15 years, told DW. 

Rulsch said quality must be gauged by individual indicators. He said a large number of contributors alone did not necessarily translate to quality content. An article that was initially "researched in detail" and factually sound would not always benefit from several changes and addenda. Moreover, it is not easy to rapidly call up the number of authors in every language version, he said. So, it is not easy to measure the quality of Wikipedia according to a formula.

Wikipedia's 'many authors'

Poor spelling and grammar can be signs that an entry is substandard, said Nenja Wolbers a project manager at Germany's Digital Opportunities Foundation, which promotes online inclusion to combat the societal digital divide. She said users should pay attention to whether an article is neutral or expresses an opinion, and whether it provides a broad overview and presents different perspectives. 

Users should be on the lookout for contradictions and should always check the sources, Wolbers said: "This is essential if I want to know if information is valid." She said it was important that quotations be referenced and that users check the sources. "It makes sense to simply click on the links," she said. Wolbers uses Wikipedia to get a general overview of a subject, but "this doesn't mean that I have a final answer." 

"Users have to remember that Wikipedia is a site used by many authors," she said, "and it is possible to modify things quickly." 

Comparing Wikipedia's languages

Articles about the same topics are written and edited independently of each other by  authors in  different languages. They may emphasize different aspects of issues; there might even be very different information. For example, entries about Crimea, which Russia annexed from Ukraine in March 2014, differ depending on the language. DW's fact-check team analyzed the German, Russian and Ukrainian entries. The German version called Crimea  a "Ukrainian peninsula," while the Russian did not mention its belonging to Ukraine, though it acknowledged a territorial dispute. The entries contained most of the same basic factual information about the region, but the entries differed on more recent events: The Ukrainian version has a section called "Annexation of Crimea," but the Russian refers to the "Accession of Crimea to the Russian Federation." Most Russian entries on the topic fail to mention that the March 2014 referendum that led to Crimea's annexation was not considered legitimate by the government of Ukraine and many international institutions, which do not recognize the annexation either.

Rulsch cited the conflict between Armenia and Azerbaijan over the territory of Nagorno-Karabakh, which flared up once again recently. "I've been seeing this conflict on Wikipedia for over 10 years," he said. "The issue is about definition — whether it was genocide or not — and who started it." Volunteers like him can work as mediators in such situations. "I don't think that there is truth and neutrality, but Wikipedia's goal is to get as close to these as possible and to strive towards them," he said. "If there is no neutral standpoint, then several standpoints can be presented." 

Wolbers recommends that users use translation tools to read Wikipedia entries in other languages, as well as to seek other sources. 

Politicians manipulating Wikipedia?

Several cases of politicians editing the entries about them have been reported. In Germany, the energy lobby has been accused of tweaking Wikipedia entries in order to "greenwash." Celebrities such as the US actor Lindsay Lohan have been declared dead. Wikipedia even has a list of fake entries in nine languages. A hoax article about a fictional extinct carnivore called a Mustelodon was online for 14 years and nine months — at least according to Wikipedia. "The more obscure a topic is, the less likely people are to read it," Rulsch said, "and, the smaller the language version is, the greater the chance of manipulation." 

There are mechanisms to prevent this, but Wikipedia often relies on users. "In theory, I could now spread conspiracy theories about antiquity, because not so many people would read them," Rulsch said. "But someone would notice if there were a link to another author, and then all my modifications would be examined carefully." 

Rulsch is very familiar with non-German pages, as he is also a "steward," which gives him access to "small Wikipedias": language versions with less than 50,000 articles and fewer than 10 administrators, to whom he provides support. He said there was generally less inclination to manipulate entries in smaller versions because there were fewer readers.

Wikipedia's control measures

To prevent manipulation, administrators can remove users who have violated the regulations. They can also protect articles so that only certain users can modify them. For example, the Bosnian-language version of the entry on the Srebrenica massacre of 1995 is protected, and the rights to edit various entries in English pertaining to sexual organs have been limited. 

Over the years, Rulsch said, a system of quality control has been developed by language versions with large numbers of users. German entries have to be given a green light before being published, for example, and only registered users are allowed to create new articles in English. Bots are also used to sift out certain words, such as vulgar terms. There is also a transparency tool for users of all language versions, which gives a history of edits and deletions. 

So is Wikipedia a credible source? Many of the entries are well-documented, checked for quality and — as opposed to reference books — often completely up-to-date, but, 20 years after its creation, the online encyclopedia is not 100% reliable, because information can be manipulated, and sometimes almost undetectably.

Therefore, Wikipedia encourages users to be attentive and use their critical judgment.

This article has been adapted from German.