Transitioning from STEM degree to Econ PhD

[ags14]

I'm a third year Physics student at Imperial College London, who is considering applying to an Econ PhD program. I cuurently have offers for a Maters in both Theoretical Physics and Economics, and am heavily weighing up both options. I have the following questions:

(i) Which Masters program would suit best for the transition? I have an offer for MSc Finance and Economics at the LSE, but I also have offers in Physics from ETH and Imperial. It seems like there could be a possibility to take Econ classes whilst purusing the Physics Masters, which is what I will do if I choose physics. Also, if I do choose the non-physics masters, will other LSE Masters courses, such as the MSc EME or 2-year MSc Economics be more beneficial?

(ii) Is it necessary to have research experience in economics? I have set up an RA placement for the summer in the Imperial Finance department, but it is not necessarily in the area I am interested in, namely behavioural economics and decision-making. I have tried (but failed) to successfully cold e-mail professors into giving me a summer reserch in these areas (which is partly why the 2 year LSE course might be better, as it gives more time to be involved in research before the PhD).

Would appreciate any insights on this.

[Elchorro]

I know it is not always required to have a degree in Economics to enroll in PhD in US. My current supervisor did his undergrad in Computer Science. You personal statement/statement of purpose would then be very important as you have to demonstrate that you know what economics is about. While you can probably take some econ courses while doing physics it is not going to be much. 

There are several benefits of the degree in economics at LSE. First, you have access to professors who are know in their fields and it's known that admission committees pay attention to reference letters. Second, it would allow you to clarify your interests and help you writing strong statement of purpose. Third, with Masters degree in Economics you can do to phd program in UK, which is shorter as it doesn't have much coursework component. If you do Masters in Physics and decide you want to do PhD in Economics anywhere in europe you will have to do second masters (this could be MRes).

EME I believe is intended for people with some preliminary knowledge of economics and applications are very competitive. I know a person with very good grades and a recommendation from well known professor from LSE and still got rejected. Your situations seems to fit more into 2 year MSc Econ program. The benefit of that is that it has conditional offer for their PhD program (conditional on getting distinction), so it's great to fall back on if you don't get admitted to Top 10.  

Research in economics is definitely beneficial although not necessary. I am in my final year of undergrad in Edinburgh, and at the time of applying I could show some software I developed for computational economists, but that was about it. I got multiple Top 10 acceptances. 

To summarize, my advise would be, if you are considering PhD in Econ, do your Masters in a related discipline. I'm sure other people may have different views. Feel free to ask any questions here or in PM.