Take cues from the literature you already have for possible data sources. Early on, search the following resources, which will either lead you directly to data or will give you vital information about who collects the type of data you need.

Government agencies and nonprofits are often the most exhaustive and credible sources of data for your research. International data is collected and published by government and intergovernmental organizations. Refer to the Economics: Statistics and Data Research Guide for resource recommendations.

See also

At the very first stages of your literature review, start taking notes on potential data sources.  Make a habit of jotting down the data used in each study you read to make it faster when you come back later in your search for data.  Also, this practice can help you see and articulate how your contribution is unique.  You might want to keep these notes in a table like the following for easy reference.

For an editable table like the one above, open this spreadsheet, save a copy for yourself, then use it to track your literature.

Search these portals to search across many sites at once. Items are usually selected for inclusion based on their relevance and quality.