Creating data sets from scratch can be hugely expensive, time consuming, may require ethical approval, a.....
Funders are increasingly requiring researchers to make their datasets openly and publicly available to ensure the funds used to create the datasets are used (and reused) most efficiently. In addition, governments and government/public bodies routinely create extensive regional and national datasets, and these datasets are often released into the public domain. In computer science, "Open Source" software is a long established tradition, resulting in millions of lines of computer code becoming freely and openly available. Also, as a result of initiatives such as "Datacite" it has become increasingly attractive to researchers to make their datasets available to ensure they accrue citations, and demonstrate impact, in the same way that that citations to publications have traditionally been used.
All this means that there are vast tranches of research data openly available. One of the first questions you should ask yourself is if you need to create data at all.
Of course, if you reuse an openly available dataset, you should abide by the terms of the reuse licence, and cite the original data set and it's creator(s).
Datasets made open for reuse by some 111 publishers, including: Central Statistics Office, city councils, government departments, Environmental Protection Agency, EuroStat, Fáilte Ireland, Geological Survey of Ireland, Health and Safety Authority, Heritage Council, Met Éireann, National Transport Authority, Office of Public Works, Ordnance Survey Ireland, Revenue Commissioners, Road Safety Authority, TUSLA, and more. New datasets and publishers are being added all the time.
Search for Dublin data under headings: Arts culture and heritage, Environment and energy, Planning and land use, Government and participation, Recreation and amenities, Population and communities, Public health and safety, Economy and innovation, Transport and infrastructure.
by Maynooth University. Tidy data sets on demographics, economy, housing, and the environment
Data sets shared by public bodies in Northern Ireland.
Whilst Accessible, Interoperable, and Resusable are not guaranteed, Google's Dataset Search works along the same lines as Google Scholar.
Gene Expression Omnibus
A public functional genomics data repository supporting MIAME-compliant data submissions.
UNICEF’s Data & Analytics (D&A) team is the global go-to for data on children. It leads the collection, validation, analysis, use and communication of the most statistically sound, internationally comparable data on the situation of children and women around the world. D&A upholds the quality, integrity and organization of these data and makes them accessible as a global public good on the data.unicef.org website.