Numbeo is a Serbian crowd-sourcedonline database of perceived consumer prices, real property prices, and quality of life metrics. The website was founded in April 2009 by former Google employee Mladen Adamović,[1][2] to enable users to share and compare information about the cost of living between countries and cities.[3] Since 2012, the website has been operated by NUMBEO DOO Beograd-Palilula, a Serbian private limited company run by Adamović.[4][2][5] According to Adamović, the website earns money through advertising and the sale of subscriptions to its API.[6]
Numbeo's crowd-sourced data can be inserted or altered by anyone accessing the website, and is not peer-reviewed.[7][8][9] Data is also manually gathered by the operator, from sources such as company and governmental websites,[10][11][12] which is done in half-year intervals;[13] it is then combined with user-generated data by giving it extra weight in the final score calculation, according to the company.[14] As of 2017, it was the largest database of user generated data about cities in the world.[15] As of 2020, this possibly applied to (user generated) data on housing prices as well.[16] The quality of life index is a combination of eight sub-indexes: purchasing power, safety, healthcare, cost of living, property price to income ratio, traffic commute time, pollution, and climate.[17][18]
The website's "Crime Index", intended to serve as an overall crime level estimate, is compiled from answers to user surveys, which have been processed by a Java-programmed backend to produce country- or city-level ratings on a 100-point scale, with higher values indicating worse crime. There is also a "Safety Index", with higher scores indicating a safer city.[19] Numbeo's data points on crime have been criticized by academics[20] and by the media as unreliable and, at times, misleading.
In 2017, a Swedish man manipulated the crime stats of the Lund, Sweden by repeatedly submitting negative ratings in this category, at a time when the relevant data set was very small. In less than a day, he succeeded in making it show up as the most dangerous city in the world on the website's "Crime Index Rate" page. He commented: "Numbeo should hardly be considered stats, it’s more like reviews. Anyone, anywhere in the world can change the data, as many times as they want. Completely anonymously."[21]
In 2022, a Numbeo claim that Bradford, England was "Europe's most dangerous city" went viral on social media and was reported on in British press.[22][23] Another English city, Coventry, was ranked second in this statistic, which was disputed by a local newspaper journalist—citing higher official crime rates in various other English cities/counties.[24]
In 2022, David Weinberger expressed criticism of the site's methodology of measuring crime rate, saying: "It is misleading to claim to have derived from this a representation of the highest-crime rate cities: what is presented are cities which are perceived as those with the most crime, by a certain number of Internet users. But for studies in the social sciences, this approach is worthless." The crime and security indices' measurements are derived from answers to a 15-point questionnaire. Experts responding to AFP's fact-checkers' inquiries regarding reliability of Numbeo's crime stats contended that this does not make for a methodologically valid victimization survey, due to non-representative sampling, and that—especially with respect to cross-country comparisons which are considered effectively impossible to validly construct (except for certain crimes that may be experienced the same way across communities, such as car theft)—the site's information is false.[20]
^Walsh, Alistair (29 August 2012). "Harare has poor healthcare and political violence, but property is relatively inexpensive". propertyobserver.com.au. Archived from the original on 18 September 2017. Serbian-run website Numbeo lists the inner-city apartment prices in Harare at $1,000 a square metre. The numbers are based on user contributed figures and should be taken with a hefty pinch of salt.
^Fox, David (28 January 2022). "Bermuda trails most countries in purchasing power". The Royal Gazette. Retrieved 3 June 2023. Numbeo also uses links to government websites, supermarket and restaurant sites with prices and other relevant sources, together with publicly available links to pricing for taxi and bus services.
^"Methodology and Motivation". www.numbeo.com. Retrieved 2 June 2023. Numbeo's data collection process involves a combination of user-generated input and manually gathered information from reputable sources such as supermarket and taxi company websites, and governmental institutions. The manually collected data from each source are entered twice yearly and given a weight that is three times higher than user-generated input to improve the reliability of the data.