How Many Volunteers Does It Take To Map An Area Well? The validity of Linus’ law to Volunteered Geographic Information

10 January, 2011

The paper “How Many Volunteers Does It Take To Map An Area Well? The validity of Linus’ law to Volunteered Geographic Information has appeared in The Cartographic Journal. The proper citation for the paper is:

Haklay, M and Basiouka, S and Antoniou, V and Ather, A (2010) How Many Volunteers Does It Take To Map An Area Well? The validity of Linus’ law to Volunteered Geographic Information. The Cartographic Journal , 47 (4) , 315 – 322.

The abstract of the paper is as follows:

In the area of volunteered geographical information (VGI), the issue of spatial data quality is a clear challenge. The data that are contributed to VGI projects do not comply with standard spatial data quality assurance procedures, and the contributors operate without central coordination and strict data collection frameworks. However, similar to the area of open source software development, it is suggested that the data hold an intrinsic quality assurance measure through the analysis of the number of contributors who have worked on a given spatial unit. The assumption that as the number of contributors increases so does the quality is known as `Linus’ Law’ within the open source community. This paper describes three studies that were carried out to evaluate this hypothesis for VGI using the OpenStreetMap dataset, showing that this rule indeed applies in the case of positional accuracy.

To access the paper on the journal’s website, you can follow the link: 10.1179/000870410X12911304958827. However, if you don’t hold a subscription to the journal, a postprint of the paper is available at the UCL Discovery repository. If you would like to get hold of the printed version, email me.

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3 Responses to “How Many Volunteers Does It Take To Map An Area Well? The validity of Linus’ law to Volunteered Geographic Information”


  1. […] sobre el tema. La serie de investigaciones realizadas tratan de responder a la pregunta… ¿cuántos voluntarios hacen falta para mapear con calidad un área?, es decir, tratan de cotejar la Ley de Linus en el ámbito de los mapas. Los resultados: para un […]


  2. […] We also know that more people looking at area’s improved accuracy. […]


  3. […] I am always skeptical of crowdsourced data or, indeed, any data. As a geographer and remote sensor whose focus is enumerating displaced populations, I have to be: skepticism is part of my job. All data contain error, so best to acknowledge it and decide what that error means. There is still a lot of uncertainty around these types of volunteered geographic information; specifically questions over the positional accuracy, precision, and validity of these data among a wide variety of other issues . These quantitative issues are important because the general assumption is that these data will be operationalized somehow and it is, therefore, imperative that they add value to already confusing situations if this enterprise is to be taken seriously in an operational sense . The good news is that research so far show that these “asserted” data are not – a priori – necessarily any worse than “authoritative” data and can be quite good due to the greater number of individuals to correct error. […]


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