Components of a Successful Ph.D. Personal Statement
A good PS presents your story. To “present” means to give concrete examples and to provide enough details that the reader is never wondering what your words mean. If the reader is confused or lost, you have lost it, so quality writing is of critical importance. “Your” means that the story should be about you. The PS needs to show who you are behind the resume. This is your chance to tell the reader that you and your ideas are bigger than what fits in a resume, so use it. You also have the chance to show your reader what you think is important and meaningful about your activities, research, and life in general, so do that as well. Show your motivations, and how your actions have followed your motivations. Describe what you have done briefly, and either why they should care about it, or what you have learned from it, or how it has shaped your outlook on the future, or how you have expressed yourself through it. Lastly, “story” means that it is nice to have some continuity, a theme, something about yourself that runs through all the experiences that you choose to show here, something that ties them all together that no one else but you could have written. Another way to say the same things more broadly and with more examples is here.
While the PS is a look at who you are, the statement of purpose (SoP) is more focused on the profession and on the future. Write about your professional mission and motivation, describe results similarly to how you would write the introduction and conclusion to an academic paper. Say just a few words about future plans and expectations.
Now, this looks like the postmortem of an essay, yet we never know neither what part of the application tips the decisions, nor how close to the cutoff the application finishes. So how do you actually write one that maximizes your chances of getting in? Here are three quick pointers to a good process:
Be genuine, and speak from your inner place of power. There is no substitute for inspiration.
Edit like crazy, and get feedback from as many relevant people as possible. 7 versions before submission is a good number.
Observe carefully how your essays make you and others feel upon being read. That feeling better be strictly positive.