If your research interests are multidisciplinary and you are unsure of what field to do your PhD in, Professor Noah Smith makes a compelling case for getting an econ PhD (https://noahpinionblog.blogspot.jp/2013/05/if-you-get-phd-get-economics-phd.html). Many professors of public policy, political science, and public health are trained as economists. Of course, econ may not be the right path for everyone, but if you do choose to apply to PhD programs in economics, check out these resources to maximize your chances of getting accepted.
- Professor Sita Slavov's tips for applying to PhD programs: https://sites.google.com/site/sitaslavov/home/advice
- Professor William Craighead's advice for econ grad school: https://sites.google.com/site/wdcraighead/grad-school-advice
- Professor Dick Startz's guide for getting accepted into econ PhD programs: http://econ.ucsb.edu/~startz/A%20Guide%20for%20UCSB%20Undergraduates%20Considering%20a%20PhD%20in%20Economics.pdf
- Professor Susan Athey's advice for applying to grad school in economics: https://people.stanford.edu/athey/professional-advice
- American Economic Association's suggested application timeline: https://www.aeaweb.org/resources/students/grad-prep/timeline
- Professor Chris Blattman's FAQ's on PhD applications: https://chrisblattman.com/about/contact/gradschool/
- Professor Greg Mankiw's advice for aspiring economists: https://gregmankiw.blogspot.com/2006/05/advice-for-aspiring-economists.html
- Professor Miles Kimball and Professor Noah Smith's guide to getting into an econ PhD program: https://www.theatlantic.com/business/archive/2013/08/the-complete-guide-to-getting-into-an-economics-phd-program/278773/
Came across any other good resources for getting accepted into Econ PhD programs? Mention them in the comments below.