evidence: While availability of green space is important, it concludes urban green spaces also need to be of high quality, when it comes to cleanliness, safety and quality of services, to be perceived as being adequate by local residents. Basing planning on metrics that use objective measures of accessible green space "is unlikely to fully capture public perceptions of the adequacy of these spaces", the study by Peter Barlow, Seán Lyons and Anne Nolan finds. [...] There is ongoing debate about how best to measure the quality, quantity, and accessibility of green space. Subjective measures (asking people to assess whether green spaces are adequate), and objective measures (directly measuring types of green space in an individual’s local area) are used.