How undergraduate research area affects Ph.D. admission chances? I would like to do a Ph.D. in CS and I will start doing research as an undergraduate student soon, and I will be applying next year (December 2014) at good (say top 15) US universities. My problem is that I have interest in many areas and I don't know which one to choose. At first, I thought that would like to do research in Machine Learning, but then I realized that there are many undergraduate students doing research in that area so it will be more difficult for me to get in a good school by having research experience at that area, as I am not coming from a highly ranked program.

In addition I am an international student, currently studying Computer Engineering and not Computer Science and this may affect my application as well. So I am thinking about doing research in another area that may be a little less competitive and choose my field of interest (it may be the same) after I got into graduate school.

So my question is:


Will it be better to choose something that is less competitive (that still interests me) as a research area for my undergraduate thesis?
Put simply: No.

Your undergraduate thesis work need not have any connection with your graduate research. Certainly, staying in the same area lets you have more of a "running start," but there's always the chance that you find a new research project as a graduate student that grabs your attention and doesn't let go. 

So don't worry too much about doing research work in a less competitive area unless you want to do that research anyway. It's better to do work that excites and motivates you, because the end product will almost certainly be better than taking a project that doesn't.