Grad school is a big decision. If you are still mulling over whether to apply for PhD programs, ask yourself these questions.
1. What am I hoping to get out of the PhD?
The way I see it, you should do a PhD if you need to or if you want to (or both). Take some time to reflect on your career goals and ask yourself if you really need a PhD to get there? If you intend to go into academia, the answer is an unequivocal yes. Nearly all academic positions, tenure-track or not, require a PhD. If you are aiming for industry, government, or non-profit jobs, the answer may not be as clear. While certain positions, particularly those in research settings, may require a PhD for promotion and career advancement, this is not always the case. Talk to people in your field to understand what the current trends are. (And remember that different people may have different perspectives, so talk to a lot of people!) Study the educational/professional backgrounds of people who are working in your "dream job" and talk to them about why they did or did not attend grad school. If you are currently an undergraduate student and not completely sure of your long-term career goals just yet, consider working in the "real world" for a couple years before applying to PhD programs. This will give you some insight on potential benefits of doing a PhD in your field.
2. Do I understand how doctoral study differs from undergraduate study, and am I prepared for PhD level research?
Although the first two years of most PhD programs involve classes, studying, textbooks, and exams, not unlike the type of work you experienced in undergrad, the crux of the PhD program is really research. And PhD-level research involves an enormous amount of dense reading, painstaking data work, weeks of writing and rewriting, presenting to less-than-friendly crowds, and responding to all sorts of criticism. You will first find yourself attending your department's research seminars, learning rigorous empirical methods, and reading academic research papers as part of your coursework; these are the types of papers that you will someday be expected to write yourself. Then you will work as a research assistant or coauthor with professors, most likely doing heavy data work and learning the ins and outs of writing an academic paper. And finally, with the guidance of your adviser and dissertation committee, you will engage in your own independent research project, culminating in your dissertation. As a PhD student, you will be judged on the quantity and quality of your research and not your grades (so long as you maintain the minimum GPA requirement and pass the qualifying exams). Know and understand that this is what you're signing yourself up for.
3. How do I feel about math?
Math is important, very important. We live in the age of data, and even fields that used to be qualitative are becoming more and more quantitative. You don't necessarily have to be a "math genius" to successfully complete the PhD, but your coursework and research will involve advanced math and it is necessary to have some level of comfort with numbers and models. If you're still an undergrad and you're even thinking about doing a PhD in the future, take all the math courses that you can now! Linear algebra, multivariable calculus, statistics, and econometrics are the bare minimum; real analysis would be nice too. And if you're already out of school, take advantage of free open courseware online to learn or re-learn these subjects. (Dr. Strang's linear algebra course on MIT open courseware is excellent.)
4. Am I financially prepared for a PhD?
Although PhD programs usually do not involve any direct costs (most full-time students receive tuition reimbursement and stipends as part of their assistantships), there are significant opportunity costs involved. During the years you spend in grad school, you could instead be working and earning substantially more than your stipend. And if your undergraduate degree is in a lucrative field, such as computer science or finance, it is very possible that the salary of your classmates who started working right away after undergrad may surpass your starting salary after you finish your PhD. Of course, money is not the only variable in one's happiness function, but give some thought to how important short-term and long-term financial success are to you and how grad school will affect that.
5. Do I have the time to research PhD programs and find the best fit for me?
When you're deciding where to apply, don't just blindly apply to the top 10 or the most popular schools in your field. Instead, take the time to explore each school, paying particular attention to:
(1) The research areas of professors. A PhD is all about research, and the last thing you want is to end up at a highly-ranked school where no faculty member is doing work in the areas that you're really interested in.
(2) Location. Remember, you will be living here for at least 5 years. Be sure the schools you apply to are located in areas where you and your family will be happy.
(3) Alumni placement. Check out each school's webpage to see what past PhD students have gone on to do. If you're aiming for an academic job, does the school have a track record of producing tenure-track faculty?
(4) Potential advisers. This is absolutely the most important factor. A great adviser is not only a well-reputed scholar but also a sincere mentor. I am fortunate to have an incredibly supportive adviser. Aside from inspiring me with her own stellar research and passion for health policy, my adviser makes herself available to me whenever I need guidance, creates opportunities for me to network with other senior professors, and gives me room to explore my interests and grow as a researcher.
So how do you find out these things? Scouring the department's website is very important: check out the faculty webpages of potential advisers, understand their research interests, and note whether senior professors are publishing papers with junior professor and grad students (this is a sign of a good mentor). Even better is to e-mail current grad students and chat with them about their experiences. And if you're very serious about a particular school, e-mail potential faculty advisers to set up times to speak with them (but don't be disheartened if they don't reply right away...professors are busy people!). All this research takes time, and before applying to programs, be sure you have the time to really find the best ones for you.
6. What does my significant other think about me getting a PhD?
If you are married or in a long-term relationship, be sure your partner understands and supports what you are getting yourself into. If you get accepted into your dream school across the country, are you prepared to live apart for five years? Grad school is not a 9-5 job. Does your partner understand that you will often have to work nights, weekends, and travel out-of-town for conferences? As a grad student, your schedule may be flexible in some ways, as nobody is expecting you to punch in and punch out at certain times, but with this flexibility comes great accountability. You are responsible for your research and as a result your work hours will probably become "whenever you find time to get things done." That being said, many successful students are married and/or have children. It is definitely possible to find that balance between professional and family life.
7. Do I love my field?
A PhD program can be long and grueling, and unless you truly love your research area, you may find yourself frustrated and ready to give up. Conversely, if you do love your field, you will find the PhD to be one of the most enjoyable and fulfilling aspects of your life. The best thing about doing a PhD is that you can really make the research your own. Although my degree is in economics, my research area is health economics, and specifically my dissertation work focuses on policies to improve access to health care and health behaviors. My daily work is not only intellectually challenging but also emotionally fulfilling. Once you become a PhD student, chances are that no matter where you are or what you're doing, somewhere in the back of your mind you'll be thinking about your research, so be sure it's something that you love.
Although there is certainly a lot to consider before applying to grad school, remember that the most important qualification for starting a Ph.D. is intense passion for research and for your field. If your experience ends up being anything like mine, then you are about to embark on an exciting journey - one that is simultaneously challenging and rewarding, and makes each day feel like a new adventure. I can say with confidence that once you find your niche and passion, the doctoral path fills your life with purpose and joy. There is nothing quite like the thrill of starting a new research project, tangling with layers of analysis trying to make sense of data, all the while knowing that your end result just may help people and improve our understanding of the world.